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AdventOfCode2024 Day04
AdventOfCode2024 Day03 Part 2
2025-08-01 06:15:44 +02:00 · 2024-12-05 01:23:46 +01:00 · 2024-12-03 12:04:17 +01:00 · 2024-12-03 11:53:06 +01:00 · 2024-12-02 08:21:07 +01:00 · 2024-12-02 07:55:58 +01:00
113 changed files with 3683 additions and 952 deletions
--- a/.editorconfig
+++ b/.editorconfig
@@ -1,10 +1,9 @@
-
 [*]

 # Microsoft .NET properties
 csharp_indent_braces = false
 csharp_new_line_before_members_in_object_initializers = false
-csharp_new_line_before_open_brace = accessors,anonymous_methods,control_blocks,events,indexers,lambdas,local_functions,methods,properties,types
+csharp_new_line_before_open_brace = accessors, anonymous_methods, control_blocks, events, indexers, lambdas, local_functions, methods, properties, types
 csharp_preferred_modifier_order = private, public, protected, internal, file, new, readonly, abstract, virtual, sealed, static, override, extern, unsafe, volatile, async, required:suggestion
 csharp_prefer_braces = true:none
 csharp_preserve_single_line_blocks = true
--- a/.idea/.idea.AdventOfCode/.idea/developer-tools.xml
+++ b/.idea/.idea.AdventOfCode/.idea/developer-tools.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="DeveloperToolsToolWindowSettingsV1" lastSelectedContentNodeId="base64-encoder-decoder">
+    <developerToolsConfigurations />
+  </component>
+</project>
--- a/.idea/.idea.AdventOfCode/.idea/dictionaries/var.xml
+++ b/.idea/.idea.AdventOfCode/.idea/dictionaries/var.xml
@@ -0,0 +1,3 @@
+<component name="ProjectDictionaryState">
+  <dictionary name="var" />
+</component>
--- a/AdventOfCode.Common/AdventOfCode.Common.csproj
+++ b/AdventOfCode.Common/AdventOfCode.Common.csproj
@@ -1,10 +1,10 @@
 <Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
-        <TargetFramework>net7.0</TargetFramework>
+        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
-        <RootNamespace>AdventOfCode.Common</RootNamespace>
        <Nullable>enable</Nullable>
+        <RootNamespace>AdventOfCode.Common</RootNamespace>
    </PropertyGroup>

 </Project>
--- a/AdventOfCode.Common/DayHelper.cs
+++ b/AdventOfCode.Common/DayHelper.cs
@@ -15,7 +15,7 @@ public static class DayHelper
        return null;
    }

-    public static void RunDay(string eventName, int dayNumber)
+    private static void RunDay(string eventName, int dayNumber)
    {
        Console.WriteLine($"Day {dayNumber:00}");
        Console.WriteLine("------");
@@ -64,7 +64,7 @@ public static class DayHelper
        }
    }

-    public static void RunDay(string eventName)
+    private static void RunDay(string eventName)
    {
        for (int currentDay = 1; currentDay < 25; currentDay++)
        {
--- a/AdventOfCode.sln
+++ b/AdventOfCode.sln
@@ -1,73 +0,0 @@
-
-Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio Version 16
-VisualStudioVersion = 16.0.30711.63
-MinimumVisualStudioVersion = 10.0.40219.1
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-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode2020.Tests", "AdventOfCode2020.Tests\AdventOfCode2020.Tests.csproj", "{2B079D7D-08D4-4FFB-A000-858FFDD945FA}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode2017", "AdventOfCode2017\AdventOfCode2017.csproj", "{49C8A67C-D94C-4CFB-B7FB-C19A1A83CA66}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode2017.Tests", "AdventOfCode2017.Tests\AdventOfCode2017.Tests.csproj", "{3537CE59-1C57-481B-85F7-3F2A1F0EDE1D}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode2018", "AdventOfCode2018\AdventOfCode2018.csproj", "{43DAF84F-369A-48C5-9292-536094336F8F}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode2018.Tests", "AdventOfCode2018.Tests\AdventOfCode2018.Tests.csproj", "{EE35694D-97C1-485D-9FFE-73912FA97446}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode2023", "AdventOfCode2023\AdventOfCode2023.csproj", "{0D90084C-D2D9-489E-BFC3-5E63AE9947B3}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode2023.Tests", "AdventOfCode2023.Tests\AdventOfCode2023.Tests.csproj", "{00869F26-F53E-451D-BEA2-4E3FFE2216FB}"
-EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode.Common", "AdventOfCode.Common\AdventOfCode.Common.csproj", "{D6C2B27F-22C3-49E2-9591-225B7132452D}"
-EndProject
-Global
-	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-		Debug|Any CPU = Debug|Any CPU
-		Release|Any CPU = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{CD1829F6-166D-4F78-AB95-C58916F42494}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{CD1829F6-166D-4F78-AB95-C58916F42494}.Debug|Any CPU.Build.0 = Debug|Any CPU
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-		{CD1829F6-166D-4F78-AB95-C58916F42494}.Release|Any CPU.Build.0 = Release|Any CPU
-		{2B079D7D-08D4-4FFB-A000-858FFDD945FA}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{2B079D7D-08D4-4FFB-A000-858FFDD945FA}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{2B079D7D-08D4-4FFB-A000-858FFDD945FA}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{2B079D7D-08D4-4FFB-A000-858FFDD945FA}.Release|Any CPU.Build.0 = Release|Any CPU
-		{49C8A67C-D94C-4CFB-B7FB-C19A1A83CA66}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{49C8A67C-D94C-4CFB-B7FB-C19A1A83CA66}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{49C8A67C-D94C-4CFB-B7FB-C19A1A83CA66}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{49C8A67C-D94C-4CFB-B7FB-C19A1A83CA66}.Release|Any CPU.Build.0 = Release|Any CPU
-		{3537CE59-1C57-481B-85F7-3F2A1F0EDE1D}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{3537CE59-1C57-481B-85F7-3F2A1F0EDE1D}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{3537CE59-1C57-481B-85F7-3F2A1F0EDE1D}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{3537CE59-1C57-481B-85F7-3F2A1F0EDE1D}.Release|Any CPU.Build.0 = Release|Any CPU
-		{43DAF84F-369A-48C5-9292-536094336F8F}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{43DAF84F-369A-48C5-9292-536094336F8F}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{43DAF84F-369A-48C5-9292-536094336F8F}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{43DAF84F-369A-48C5-9292-536094336F8F}.Release|Any CPU.Build.0 = Release|Any CPU
-		{EE35694D-97C1-485D-9FFE-73912FA97446}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{EE35694D-97C1-485D-9FFE-73912FA97446}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{EE35694D-97C1-485D-9FFE-73912FA97446}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{EE35694D-97C1-485D-9FFE-73912FA97446}.Release|Any CPU.Build.0 = Release|Any CPU
-		{0D90084C-D2D9-489E-BFC3-5E63AE9947B3}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{0D90084C-D2D9-489E-BFC3-5E63AE9947B3}.Debug|Any CPU.Build.0 = Debug|Any CPU
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-		{00869F26-F53E-451D-BEA2-4E3FFE2216FB}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{00869F26-F53E-451D-BEA2-4E3FFE2216FB}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{00869F26-F53E-451D-BEA2-4E3FFE2216FB}.Release|Any CPU.Build.0 = Release|Any CPU
-		{D6C2B27F-22C3-49E2-9591-225B7132452D}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{D6C2B27F-22C3-49E2-9591-225B7132452D}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{D6C2B27F-22C3-49E2-9591-225B7132452D}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{D6C2B27F-22C3-49E2-9591-225B7132452D}.Release|Any CPU.Build.0 = Release|Any CPU
-	EndGlobalSection
-	GlobalSection(SolutionProperties) = preSolution
-		HideSolutionNode = FALSE
-	EndGlobalSection
-	GlobalSection(ExtensibilityGlobals) = postSolution
-		SolutionGuid = {4BAE59D7-7AFF-42B6-A391-CD22CD443B03}
-	EndGlobalSection
-EndGlobal
--- a/AdventOfCode.sln.DotSettings
+++ b/AdventOfCode.sln.DotSettings
@@ -6,9 +6,12 @@
 	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/Abbreviations/=VY/@EntryIndexedValue">VY</s:String>
 	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/PredefinedNamingRules/=Locals/@EntryIndexedValue">&lt;Policy Inspect="True" Prefix="" Suffix="" Style="aaBb_AaBb" /&gt;</s:String>
 	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/PredefinedNamingRules/=TypesAndNamespaces/@EntryIndexedValue">&lt;Policy Inspect="True" Prefix="" Suffix="" Style="AaBb_AaBb" /&gt;</s:String>
+	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/UserRules/=61a991a4_002Dd0a3_002D4d19_002D90a5_002Df8f4d75c30c1/@EntryIndexedValue">&lt;Policy&gt;&lt;Descriptor Staticness="Any" AccessRightKinds="Any" Description="Local variables"&gt;&lt;ElementKinds&gt;&lt;Kind Name="LOCAL_VARIABLE" /&gt;&lt;/ElementKinds&gt;&lt;/Descriptor&gt;&lt;Policy Inspect="True" Prefix="" Suffix="" Style="aaBb_AaBb" /&gt;&lt;/Policy&gt;</s:String>
+	<s:String x:Key="/Default/CodeStyle/Naming/CSharpNaming/UserRules/=a0b4bc4d_002Dd13b_002D4a37_002Db37e_002Dc9c6864e4302/@EntryIndexedValue">&lt;Policy&gt;&lt;Descriptor Staticness="Any" AccessRightKinds="Any" Description="Types and namespaces"&gt;&lt;ElementKinds&gt;&lt;Kind Name="NAMESPACE" /&gt;&lt;Kind Name="CLASS" /&gt;&lt;Kind Name="STRUCT" /&gt;&lt;Kind Name="ENUM" /&gt;&lt;Kind Name="DELEGATE" /&gt;&lt;/ElementKinds&gt;&lt;/Descriptor&gt;&lt;Policy Inspect="True" Prefix="" Suffix="" Style="AaBb_AaBb" /&gt;&lt;/Policy&gt;</s:String>
 	<s:Boolean x:Key="/Default/Environment/Filtering/ExcludeCoverageFilters/=AdventOfCode_002A_002ETests_003B_002A_003B_002A_003B_002A/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/Filtering/ExcludeCoverageFilters/=AdventOfCode_002ECommon_003B_002A_003B_002A_003B_002A/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/Filtering/ExcludeCoverageFilters/=_002A_003B_002A_003BProgram_003B_002A/@EntryIndexedValue">True</s:Boolean>
+	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ESettingsUpgrade_002EPredefinedNamingRulesToUserRulesUpgrade/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=Chrono/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=Extrapolator/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/UserDictionary/Words/=extrapolators/@EntryIndexedValue">True</s:Boolean></wpf:ResourceDictionary>
--- a/AdventOfCode.slnx
+++ b/AdventOfCode.slnx
@@ -0,0 +1,13 @@
+<Solution>
+    <Project Path="AdventOfCode.Common\AdventOfCode.Common.csproj" Type="Classic C#"/>
+    <Project Path="AdventOfCode2017.Tests\AdventOfCode2017.Tests.csproj" Type="Classic C#"/>
+    <Project Path="AdventOfCode2017\AdventOfCode2017.csproj" Type="Classic C#"/>
+    <Project Path="AdventOfCode2018.Tests\AdventOfCode2018.Tests.csproj" Type="Classic C#"/>
+    <Project Path="AdventOfCode2018\AdventOfCode2018.csproj" Type="Classic C#"/>
+    <Project Path="AdventOfCode2020.Tests\AdventOfCode2020.Tests.csproj" Type="Classic C#"/>
+    <Project Path="AdventOfCode2020\AdventOfCode2020.csproj"/>
+    <Project Path="AdventOfCode2023.Tests\AdventOfCode2023.Tests.csproj" Type="Classic C#"/>
+    <Project Path="AdventOfCode2023\AdventOfCode2023.csproj" Type="Classic C#"/>
+    <Project Path="AdventOfCode2024.Tests\AdventOfCode2024.Tests.csproj" Type="Classic C#"/>
+    <Project Path="AdventOfCode2024\AdventOfCode2024.csproj" Type="Classic C#"/>
+</Solution>
--- a/AdventOfCode2017.Tests/AdventOfCode2017.Tests.csproj
+++ b/AdventOfCode2017.Tests/AdventOfCode2017.Tests.csproj
@@ -1,16 +1,18 @@
 <Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
-    <TargetFramework>net7.0</TargetFramework>
+        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
        <RootNamespace>AdventOfCode2017.Tests</RootNamespace>

        <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
    </PropertyGroup>

    <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-    <PackageReference Include="xunit" Version="2.6.3" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0"/>
+        <PackageReference Include="xunit" Version="2.6.3"/>
        <PackageReference Include="xunit.runner.visualstudio" Version="2.5.5">
            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
            <PrivateAssets>all</PrivateAssets>
@@ -18,7 +20,7 @@
    </ItemGroup>

    <ItemGroup>
-    <ProjectReference Include="..\AdventOfCode2017\AdventOfCode2017.csproj" />
+        <ProjectReference Include="..\AdventOfCode2017\AdventOfCode2017.csproj"/>
    </ItemGroup>

 </Project>
--- a/AdventOfCode2017.Tests/Day01_Tests.cs
+++ b/AdventOfCode2017.Tests/Day01_Tests.cs
@@ -9,7 +9,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart1(new[] { "1122", });
+        string result = day01.ResolvePart1(["1122"]);

        Assert.Equal("3", result);
    }
@@ -19,7 +19,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart1(new[] { "1111", });
+        string result = day01.ResolvePart1(["1111"]);

        Assert.Equal("4", result);
    }
@@ -29,7 +29,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart1(new[] { "1234", });
+        string result = day01.ResolvePart1(["1234"]);

        Assert.Equal("0", result);
    }
@@ -39,7 +39,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart1(new[] { "91212129", });
+        string result = day01.ResolvePart1(["91212129"]);

        Assert.Equal("9", result);
    }
@@ -53,7 +53,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart2(new[] { "1212", });
+        string result = day01.ResolvePart2(["1212"]);

        Assert.Equal("6", result);
    }
@@ -63,7 +63,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart2(new[] { "1221", });
+        string result = day01.ResolvePart2(["1221"]);

        Assert.Equal("0", result);
    }
@@ -73,7 +73,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart2(new[] { "123425", });
+        string result = day01.ResolvePart2(["123425"]);

        Assert.Equal("4", result);
    }
@@ -83,7 +83,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart2(new[] { "123123", });
+        string result = day01.ResolvePart2(["123123"]);

        Assert.Equal("12", result);
    }
@@ -93,7 +93,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart2(new[] { "12131415", });
+        string result = day01.ResolvePart2(["12131415"]);

        Assert.Equal("4", result);
    }
--- a/AdventOfCode2017.Tests/Day02_Tests.cs
+++ b/AdventOfCode2017.Tests/Day02_Tests.cs
@@ -7,11 +7,11 @@ public class Day02_Tests
    {
        Day02 day02 = new();

-        string result = day02.ResolvePart1(new[] {
+        string result = day02.ResolvePart1([
            "5 1 9 5",
            "7 5 3",
            "2 4 6 8",
-        });
+        ]);

        Assert.Equal("18", result);
    }
@@ -21,11 +21,11 @@ public class Day02_Tests
    {
        Day02 day02 = new();

-        string result = day02.ResolvePart2(new[] {
+        string result = day02.ResolvePart2([
            "5 9 2 8",
            "9 4 7 3",
            "3 8 6 5",
-        });
+        ]);

        Assert.Equal("9", result);
    }
--- a/AdventOfCode2017.Tests/packages.config
+++ b/AdventOfCode2017.Tests/packages.config
@@ -1,5 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<packages>
-  <package id="MSTest.TestAdapter" version="1.3.2" targetFramework="net461" />
-  <package id="MSTest.TestFramework" version="1.3.2" targetFramework="net461" />
-</packages>
--- a/AdventOfCode2017/AdventOfCode2017.csproj
+++ b/AdventOfCode2017/AdventOfCode2017.csproj
@@ -2,8 +2,9 @@

    <PropertyGroup>
        <OutputType>Exe</OutputType>
-    <TargetFramework>net7.0</TargetFramework>
+        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
        <RootNamespace>AdventOfCode2017</RootNamespace>
    </PropertyGroup>

@@ -14,7 +15,7 @@
    </ItemGroup>

    <ItemGroup>
-    <ProjectReference Include="..\AdventOfCode.Common\AdventOfCode.Common.csproj" />
+        <ProjectReference Include="..\AdventOfCode.Common\AdventOfCode.Common.csproj"/>
    </ItemGroup>

 </Project>
--- a/AdventOfCode2017/Day01.cs
+++ b/AdventOfCode2017/Day01.cs
@@ -48,10 +48,10 @@ public class Day01 : IDay
    {
        string input = inputs[0];
        int value = 0;
-        for(int i = 0; i < input.Length; i++)
+        for (int i = 0; i < input.Length; i++)
        {
            int nextI = (i + 1) % input.Length;
-            if(input[i] == input[nextI])
+            if (input[i] == input[nextI])
            {
                value += (input[i] - '0');
            }
--- a/AdventOfCode2017/Day02.cs
+++ b/AdventOfCode2017/Day02.cs
@@ -51,10 +51,10 @@ public class Day02 : IDay
    public string ResolvePart1(string[] inputs)
    {
        int checksum = 0;
-        foreach(string input in inputs)
+        foreach (string input in inputs)
        {
            int[] row = input
-                .Split(new[] { " ", "	" }, StringSplitOptions.RemoveEmptyEntries)
+                .Split([" ", "	"], StringSplitOptions.RemoveEmptyEntries)
                .Select(cell => Convert.ToInt32(cell))
                .ToArray();
            int max = row.Max();
@@ -70,7 +70,7 @@ public class Day02 : IDay
        foreach (string input in inputs)
        {
            int[] row = input
-                .Split(new[] { " ", "	" }, StringSplitOptions.RemoveEmptyEntries)
+                .Split([" ", "	"], StringSplitOptions.RemoveEmptyEntries)
                .Select(cell => Convert.ToInt32(cell))
                .ToArray();

--- a/AdventOfCode2017/Day03.cs
+++ b/AdventOfCode2017/Day03.cs
@@ -30,11 +30,11 @@ public class Day03 : IDay
 {
    public string ResolvePart1(string[] inputs)
    {
-        return null;
+        return string.Empty;
    }

    public string ResolvePart2(string[] inputs)
    {
-        return null;
+        return string.Empty;
    }
 }
--- a/AdventOfCode2018.Tests/AdventOfCode2018.Tests.csproj
+++ b/AdventOfCode2018.Tests/AdventOfCode2018.Tests.csproj
@@ -1,16 +1,18 @@
 <Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
-    <TargetFramework>net7.0</TargetFramework>
+        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
        <RootNamespace>AdventOfCode2018.Tests</RootNamespace>

        <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
    </PropertyGroup>

    <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-    <PackageReference Include="xunit" Version="2.6.3" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0"/>
+        <PackageReference Include="xunit" Version="2.6.3"/>
        <PackageReference Include="xunit.runner.visualstudio" Version="2.5.5">
            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
            <PrivateAssets>all</PrivateAssets>
@@ -18,7 +20,7 @@
    </ItemGroup>

    <ItemGroup>
-    <ProjectReference Include="..\AdventOfCode2018\AdventOfCode2018.csproj" />
+        <ProjectReference Include="..\AdventOfCode2018\AdventOfCode2018.csproj"/>
    </ItemGroup>

 </Project>
--- a/AdventOfCode2018.Tests/Day01_Tests.cs
+++ b/AdventOfCode2018.Tests/Day01_Tests.cs
@@ -9,7 +9,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart1(new[] { "+1", "-2", "+3", "+1", });
+        string result = day01.ResolvePart1(["+1", "-2", "+3", "+1"]);

        Assert.Equal("3", result);
    }
@@ -19,7 +19,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart1(new[] { "+1", "+1", "+1", });
+        string result = day01.ResolvePart1(["+1", "+1", "+1"]);

        Assert.Equal("3", result);
    }
@@ -29,7 +29,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart1(new[] { "+1", "+1", "-2", });
+        string result = day01.ResolvePart1(["+1", "+1", "-2"]);

        Assert.Equal("0", result);
    }
@@ -39,7 +39,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart1(new[] { "-1", "-2", "-3", });
+        string result = day01.ResolvePart1(["-1", "-2", "-3"]);

        Assert.Equal("-6", result);
    }
@@ -53,7 +53,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart2(new[] { "+1", "-2", "+3", "+1", });
+        string result = day01.ResolvePart2(["+1", "-2", "+3", "+1"]);

        Assert.Equal("2", result);
    }
@@ -63,7 +63,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart2(new[] { "+1", "-1", });
+        string result = day01.ResolvePart2(["+1", "-1"]);

        Assert.Equal("0", result);
    }
@@ -73,7 +73,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart2(new[] { "+3", "+3", "+4", "-2", "-4", });
+        string result = day01.ResolvePart2(["+3", "+3", "+4", "-2", "-4"]);

        Assert.Equal("10", result);
    }
@@ -83,7 +83,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart2(new[] { "-6", "+3", "+8", "+5", "-6", });
+        string result = day01.ResolvePart2(["-6", "+3", "+8", "+5", "-6"]);

        Assert.Equal("5", result);
    }
@@ -93,7 +93,7 @@ public class Day01_Tests
    {
        Day01 day01 = new();

-        string result = day01.ResolvePart2(new[] { "+7", "+7", "-2", "-7", "-4", });
+        string result = day01.ResolvePart2(["+7", "+7", "-2", "-7", "-4"]);

        Assert.Equal("14", result);
    }
--- a/AdventOfCode2018.Tests/Day02_Tests.cs
+++ b/AdventOfCode2018.Tests/Day02_Tests.cs
@@ -7,7 +7,7 @@ public class Day02_Tests
    {
        Day02 day02 = new();

-        string result = day02.ResolvePart1(new[] {
+        string result = day02.ResolvePart1([
            "abcdef",
            "bababc",
            "abbcde",
@@ -15,7 +15,7 @@ public class Day02_Tests
            "aabcdd",
            "abcdee",
            "ababab",
-        });
+        ]);

        Assert.Equal("12", result);
    }
@@ -25,7 +25,7 @@ public class Day02_Tests
    {
        Day02 day02 = new();

-        string result = day02.ResolvePart2(new[] {
+        string result = day02.ResolvePart2([
            "abcde",
            "fghij",
            "klmno",
@@ -33,7 +33,7 @@ public class Day02_Tests
            "fguij",
            "axcye",
            "wvxyz",
-        });
+        ]);

        Assert.Equal("fgij", result);
    }
--- a/AdventOfCode2018.Tests/Day03_Tests.cs
+++ b/AdventOfCode2018.Tests/Day03_Tests.cs
@@ -96,11 +96,11 @@ public class Day03_Tests
    {
        Day03 day03 = new();

-        string result = day03.ResolvePart1(new[] {
+        string result = day03.ResolvePart1([
            "#1 @ 1,3: 4x4",
            "#2 @ 3,1: 4x4",
            "#3 @ 5,5: 2x2",
-        });
+        ]);

        Assert.Equal("4", result);
    }
@@ -110,11 +110,11 @@ public class Day03_Tests
    {
        Day03 day03 = new();

-        string result = day03.ResolvePart2(new[] {
+        string result = day03.ResolvePart2([
            "#1 @ 1,3: 4x4",
            "#2 @ 3,1: 4x4",
            "#3 @ 5,5: 2x2",
-        });
+        ]);

        Assert.Equal("3", result);
    }
--- a/AdventOfCode2018.Tests/Day04_Tests.cs
+++ b/AdventOfCode2018.Tests/Day04_Tests.cs
@@ -50,7 +50,7 @@ public class Day04_Tests
    [Fact]
    public void GuardEvent_FromStringArray__TestBase()
    {
-        List<Day04.GuardEvent> guardEvents = Day04.GuardEvent.FromStringArray(new[] {
+        List<Day04.GuardEvent> guardEvents = Day04.GuardEvent.FromStringArray([
            "[1518-11-01 00:00] Guard #10 begins shift",
            "[1518-11-01 00:05] falls asleep",
            "[1518-11-01 00:25] wakes up",
@@ -59,7 +59,7 @@ public class Day04_Tests
            "[1518-11-01 23:58] Guard #99 begins shift",
            "[1518-11-02 00:40] falls asleep",
            "[1518-11-02 00:50] wakes up",
-        });
+        ]);

        Assert.Equal(10, guardEvents[0].ID);
        Assert.Equal(Day04.GuardEventType.ShiftBegin, guardEvents[0].Type);
@@ -89,7 +89,7 @@ public class Day04_Tests
    [Fact]
    public void GuardEvent_FromStringArray__TestBaseUnsorted()
    {
-        List<Day04.GuardEvent> guardEvents = Day04.GuardEvent.FromStringArray(new[] {
+        List<Day04.GuardEvent> guardEvents = Day04.GuardEvent.FromStringArray([
            "[1518-11-01 00:00] Guard #10 begins shift",
            "[1518-11-01 23:58] Guard #99 begins shift",
            "[1518-11-01 00:30] falls asleep",
@@ -98,7 +98,7 @@ public class Day04_Tests
            "[1518-11-02 00:50] wakes up",
            "[1518-11-01 00:55] wakes up",
            "[1518-11-01 00:25] wakes up",
-        });
+        ]);

        Assert.Equal(10, guardEvents[0].ID);
        Assert.Equal(Day04.GuardEventType.ShiftBegin, guardEvents[0].Type);
@@ -132,7 +132,7 @@ public class Day04_Tests
    {
        Day04 day04 = new();

-        string result = day04.ResolvePart1(new[] {
+        string result = day04.ResolvePart1([
            "[1518-11-01 00:00] Guard #10 begins shift",
            "[1518-11-01 00:05] falls asleep",
            "[1518-11-01 00:25] wakes up",
@@ -150,7 +150,7 @@ public class Day04_Tests
            "[1518-11-05 00:03] Guard #99 begins shift",
            "[1518-11-05 00:45] falls asleep",
            "[1518-11-05 00:55] wakes up",
-        });
+        ]);

        Assert.Equal("240", result);
    }
@@ -160,7 +160,7 @@ public class Day04_Tests
    {
        Day04 day04 = new();

-        string result = day04.ResolvePart1(new[] {
+        string result = day04.ResolvePart1([
            "[1518-11-04 00:36] falls asleep",
            "[1518-11-04 00:46] wakes up",
            "[1518-11-05 00:03] Guard #99 begins shift",
@@ -178,7 +178,7 @@ public class Day04_Tests
            "[1518-11-01 00:55] wakes up",
            "[1518-11-01 23:58] Guard #99 begins shift",
            "[1518-11-05 00:55] wakes up",
-        });
+        ]);

        Assert.Equal("240", result);
    }
@@ -189,7 +189,7 @@ public class Day04_Tests
    {
        Day04 day04 = new();

-        string result = day04.ResolvePart2(new[] {
+        string result = day04.ResolvePart2([
            "[1518-11-01 00:00] Guard #10 begins shift",
            "[1518-11-01 00:05] falls asleep",
            "[1518-11-01 00:25] wakes up",
@@ -207,7 +207,7 @@ public class Day04_Tests
            "[1518-11-05 00:03] Guard #99 begins shift",
            "[1518-11-05 00:45] falls asleep",
            "[1518-11-05 00:55] wakes up",
-        });
+        ]);

        Assert.Equal("4455", result);
    }
@@ -217,7 +217,7 @@ public class Day04_Tests
    {
        Day04 day04 = new();

-        string result = day04.ResolvePart2(new[] {
+        string result = day04.ResolvePart2([
            "[1518-11-04 00:36] falls asleep",
            "[1518-11-04 00:46] wakes up",
            "[1518-11-05 00:03] Guard #99 begins shift",
@@ -235,7 +235,7 @@ public class Day04_Tests
            "[1518-11-01 00:55] wakes up",
            "[1518-11-01 23:58] Guard #99 begins shift",
            "[1518-11-05 00:55] wakes up",
-        });
+        ]);

        Assert.Equal("4455", result);
    }
--- a/AdventOfCode2018.Tests/Day05_Tests.cs
+++ b/AdventOfCode2018.Tests/Day05_Tests.cs
@@ -7,7 +7,7 @@ public class Day05_Tests
    {
        Day05 day05 = new();

-        string result = day05.ResolvePart1(new[] { "dabAcCaCBAcCcaDA" });
+        string result = day05.ResolvePart1(["dabAcCaCBAcCcaDA"]);

        Assert.Equal("10", result);
    }
@@ -17,7 +17,7 @@ public class Day05_Tests
    {
        Day05 day05 = new();

-        string result = day05.ResolvePart2(new[] { "dabAcCaCBAcCcaDA" });
+        string result = day05.ResolvePart2(["dabAcCaCBAcCcaDA"]);

        Assert.Equal("4", result);
    }
--- a/AdventOfCode2018.Tests/Day06_Tests.cs
+++ b/AdventOfCode2018.Tests/Day06_Tests.cs
@@ -7,28 +7,28 @@ public class Day06_Tests
    [Fact]
    public void ChronoPoint_FromString__Test1()
    {
-        Day06.ChronoPoint point = Day06.ChronoPoint.FromString("1, 1");
+        Day06.ChronoPoint? point = Day06.ChronoPoint.FromString("1, 1");

-        Assert.Equal(1, point.X);
-        Assert.Equal(1, point.Y);
+        Assert.Equal(1, point?.X);
+        Assert.Equal(1, point?.Y);
    }

    [Fact]
    public void ChronoPoint_FromString__Test2()
    {
-        Day06.ChronoPoint point = Day06.ChronoPoint.FromString("1, 6");
+        Day06.ChronoPoint? point = Day06.ChronoPoint.FromString("1, 6");

-        Assert.Equal(1, point.X);
-        Assert.Equal(6, point.Y);
+        Assert.Equal(1, point?.X);
+        Assert.Equal(6, point?.Y);
    }

    [Fact]
    public void ChronoPoint_FromString__Test3()
    {
-        Day06.ChronoPoint point = Day06.ChronoPoint.FromString("8, 9");
+        Day06.ChronoPoint? point = Day06.ChronoPoint.FromString("8, 9");

-        Assert.Equal(8, point.X);
-        Assert.Equal(9, point.Y);
+        Assert.Equal(8, point?.X);
+        Assert.Equal(9, point?.Y);
    }

    #endregion ChronoPoint_FromString
@@ -38,8 +38,11 @@ public class Day06_Tests
    [Fact]
    public void ChronoPoint_ManhattanDistance__Test1()
    {
-        Day06.ChronoPoint p0 = Day06.ChronoPoint.FromString("8, 9");
-        Day06.ChronoPoint p1 = Day06.ChronoPoint.FromString("1, 6");
+        Day06.ChronoPoint? p0 = Day06.ChronoPoint.FromString("8, 9");
+        Day06.ChronoPoint? p1 = Day06.ChronoPoint.FromString("1, 6");
+
+        Assert.NotNull(p0);
+        Assert.NotNull(p1);
        
        int distance = Day06.ChronoPoint.ManhattanDistance(p0, p1);

@@ -49,8 +52,11 @@ public class Day06_Tests
    [Fact]
    public void ChronoPoint_ManhattanDistance__Test2()
    {
-        Day06.ChronoPoint p0 = Day06.ChronoPoint.FromString("1, 1");
-        Day06.ChronoPoint p1 = Day06.ChronoPoint.FromString("1, 6");
+        Day06.ChronoPoint? p0 = Day06.ChronoPoint.FromString("1, 1");
+        Day06.ChronoPoint? p1 = Day06.ChronoPoint.FromString("1, 6");
+
+        Assert.NotNull(p0);
+        Assert.NotNull(p1);
        
        int distance = Day06.ChronoPoint.ManhattanDistance(p0, p1);

@@ -64,14 +70,14 @@ public class Day06_Tests
    {
        Day06 day06 = new();

-        string result = day06.ResolvePart1(new[] {
+        string result = day06.ResolvePart1([
            "1, 1",
            "1, 6",
            "8, 3",
            "3, 4",
            "5, 5",
            "8, 9",
-        });
+        ]);

        Assert.Equal("17", result);
    }
@@ -79,16 +85,16 @@ public class Day06_Tests
    [Fact]
    public void ResolvePart2__Test()
    {
-        Day06 day06 = new() { DistanceThresold = 32, };
+        Day06 day06 = new() { DistanceThreshold = 32, };

-        string result = day06.ResolvePart2(new[] {
+        string result = day06.ResolvePart2([
            "1, 1",
            "1, 6",
            "8, 3",
            "3, 4",
            "5, 5",
            "8, 9",
-        });
+        ]);

        Assert.Equal("16", result);
    }
--- a/AdventOfCode2018.Tests/Day07_Tests.cs
+++ b/AdventOfCode2018.Tests/Day07_Tests.cs
@@ -7,7 +7,7 @@ public class Day07_Tests
    {
        Day07 day07 = new();

-        string result = day07.ResolvePart1(new[] {
+        string result = day07.ResolvePart1([
            "Step C must be finished before step A can begin.",
            "Step C must be finished before step F can begin.",
            "Step A must be finished before step B can begin.",
@@ -15,7 +15,7 @@ public class Day07_Tests
            "Step B must be finished before step E can begin.",
            "Step D must be finished before step E can begin.",
            "Step F must be finished before step E can begin.",
-        });
+        ]);

        Assert.Equal("CABDFE", result);
    }
@@ -25,7 +25,7 @@ public class Day07_Tests
    {
        Day07 day07 = new() { BaseCost = 0, NumberOfWorkers = 2 };

-        string result = day07.ResolvePart2(new[] {
+        string result = day07.ResolvePart2([
            "Step C must be finished before step A can begin.",
            "Step C must be finished before step F can begin.",
            "Step A must be finished before step B can begin.",
@@ -33,7 +33,7 @@ public class Day07_Tests
            "Step B must be finished before step E can begin.",
            "Step D must be finished before step E can begin.",
            "Step F must be finished before step E can begin.",
-        });
+        ]);

        Assert.Equal("15", result);
    }
--- a/AdventOfCode2018.Tests/Day08_Tests.cs
+++ b/AdventOfCode2018.Tests/Day08_Tests.cs
@@ -34,7 +34,7 @@ public class Day08_Tests
    {
        Day08 day = new();

-        string result = day.ResolvePart1(new[] { "2 3 0 3 10 11 12 1 1 0 1 99 2 1 1 2", });
+        string result = day.ResolvePart1(["2 3 0 3 10 11 12 1 1 0 1 99 2 1 1 2"]);

        Assert.Equal("138", result);
    }
@@ -44,7 +44,7 @@ public class Day08_Tests
    {
        Day08 day = new();

-        string result = day.ResolvePart2(new[] { "2 3 0 3 10 11 12 1 1 0 1 99 2 1 1 2", });
+        string result = day.ResolvePart2(["2 3 0 3 10 11 12 1 1 0 1 99 2 1 1 2"]);

        Assert.Equal("66", result);
    }
--- a/AdventOfCode2018.Tests/Day09_Tests.cs
+++ b/AdventOfCode2018.Tests/Day09_Tests.cs
@@ -77,7 +77,7 @@ public class Day09_Tests
    {
        Day09 day = new();

-        string result = day.ResolvePart1(new[] { "9 players; last marble is worth 25 points" });
+        string result = day.ResolvePart1(["9 players; last marble is worth 25 points"]);

        Assert.Equal("32", result);
    }
@@ -87,7 +87,7 @@ public class Day09_Tests
    {
        Day09 day = new();

-        string result = day.ResolvePart1(new[] { "10 players; last marble is worth 1618 points" });
+        string result = day.ResolvePart1(["10 players; last marble is worth 1618 points"]);

        Assert.Equal("8317", result);
    }
@@ -97,7 +97,7 @@ public class Day09_Tests
    {
        Day09 day = new();

-        string result = day.ResolvePart1(new[] { "13 players; last marble is worth 7999 points" });
+        string result = day.ResolvePart1(["13 players; last marble is worth 7999 points"]);

        Assert.Equal("146373", result);
    }
@@ -107,7 +107,7 @@ public class Day09_Tests
    {
        Day09 day = new();

-        string result = day.ResolvePart1(new[] { "17 players; last marble is worth 1104 points" });
+        string result = day.ResolvePart1(["17 players; last marble is worth 1104 points"]);

        Assert.Equal("2764", result);
    }
@@ -117,7 +117,7 @@ public class Day09_Tests
    {
        Day09 day = new();

-        string result = day.ResolvePart1(new[] { "21 players; last marble is worth 6111 points" });
+        string result = day.ResolvePart1(["21 players; last marble is worth 6111 points"]);

        Assert.Equal("54718", result);
    }
@@ -127,7 +127,7 @@ public class Day09_Tests
    {
        Day09 day = new();

-        string result = day.ResolvePart1(new[] { "30 players; last marble is worth 5807 points" });
+        string result = day.ResolvePart1(["30 players; last marble is worth 5807 points"]);

        Assert.Equal("37305", result);
    }
--- a/AdventOfCode2018.Tests/Day10_Tests.cs
+++ b/AdventOfCode2018.Tests/Day10_Tests.cs
@@ -7,7 +7,7 @@ public class Day10_Tests
    {
        Day10 day = new() { Width = 12, Height = 10 };

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "position=< 9,  1> velocity=< 0,  2>",
            "position=< 7,  0> velocity=<-1,  0>",
            "position=< 3, -2> velocity=<-1,  1>",
@@ -39,7 +39,7 @@ public class Day10_Tests
            "position=< 5,  9> velocity=< 1, -2>",
            "position=<14,  7> velocity=<-2,  0>",
            "position=<-3,  6> velocity=< 2, -1>",
-        });
+        ]);

        Assert.Equal(
            Environment.NewLine + "............" +
@@ -59,7 +59,7 @@ public class Day10_Tests
    {
        Day10 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "position=< 9,  1> velocity=< 0,  2>",
            "position=< 7,  0> velocity=<-1,  0>",
            "position=< 3, -2> velocity=<-1,  1>",
@@ -91,7 +91,7 @@ public class Day10_Tests
            "position=< 5,  9> velocity=< 1, -2>",
            "position=<14,  7> velocity=<-2,  0>",
            "position=<-3,  6> velocity=< 2, -1>",
-        });
+        ]);

        Assert.Equal("3", result);
    }
--- a/AdventOfCode2018.Tests/Day11_Tests.cs
+++ b/AdventOfCode2018.Tests/Day11_Tests.cs
@@ -59,7 +59,7 @@ public class Day11_Tests
    public void ResolvePart2__Test1()
    {
        Day11 day = new();
-        string result = day.ResolvePart2(new[] { "18" });
+        string result = day.ResolvePart2(["18"]);
        Assert.Equal("90,269,16", result);
    }

@@ -67,7 +67,7 @@ public class Day11_Tests
    public void ResolvePart2__Test2()
    {
        Day11 day = new();
-        string result = day.ResolvePart2(new[] { "42" });
+        string result = day.ResolvePart2(["42"]);
        Assert.Equal("232,251,12", result);
    }
 }
--- a/AdventOfCode2018.Tests/Day12_Tests.cs
+++ b/AdventOfCode2018.Tests/Day12_Tests.cs
@@ -7,8 +7,7 @@ public class Day12_Tests
    {
        Day12 day = new();

-        string result = day.ResolvePart1(new[]
-        {
+        string result = day.ResolvePart1([
            "initial state: #..#.#..##......###...###",
            "",
            "...## => #",
@@ -25,7 +24,7 @@ public class Day12_Tests
            "###.. => #",
            "###.# => #",
            "####. => #",
-        });
+        ]);

        Assert.Equal("325", result);
    }
--- a/AdventOfCode2018.Tests/Day13_Tests.cs
+++ b/AdventOfCode2018.Tests/Day13_Tests.cs
@@ -7,7 +7,7 @@ public class Day13_Tests
    {
        Day13 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "|",
            "v",
            "|",
@@ -15,7 +15,7 @@ public class Day13_Tests
            "|",
            "^",
            "|",
-        });
+        ]);

        Assert.Equal("0,3", result);
    }
@@ -25,14 +25,14 @@ public class Day13_Tests
    {
        Day13 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            @"/->-\        ",
            @"|   |  /----\",
            @"| /-+--+-\  |",
            @"| | |  | v  |",
            @"\-+-/  \-+--/",
            @"  \------/   ",
-        });
+        ]);

        Assert.Equal("7,3", result);
    }
@@ -42,7 +42,7 @@ public class Day13_Tests
    {
        Day13 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            @"/>-<\  ",
            @"|   |  ",
            @"| /<+-\",
@@ -50,7 +50,7 @@ public class Day13_Tests
            @"\>+</ |",
            @"  |   ^",
            @"  \<->/",
-        });
+        ]);

        Assert.Equal("6,4", result);
    }
--- a/AdventOfCode2018.Tests/Day14_Tests.cs
+++ b/AdventOfCode2018.Tests/Day14_Tests.cs
@@ -9,7 +9,7 @@ public class Day14_Tests
    {
        Day14 day = new();

-        string result = day.ResolvePart1(new[] { "9", });
+        string result = day.ResolvePart1(["9"]);

        Assert.Equal("5158916779", result);
    }
@@ -19,7 +19,7 @@ public class Day14_Tests
    {
        Day14 day = new();

-        string result = day.ResolvePart1(new[] { "5", });
+        string result = day.ResolvePart1(["5"]);

        Assert.Equal("0124515891", result);
    }
@@ -29,7 +29,7 @@ public class Day14_Tests
    {
        Day14 day = new();

-        string result = day.ResolvePart1(new[] { "18", });
+        string result = day.ResolvePart1(["18"]);

        Assert.Equal("9251071085", result);
    }
@@ -39,7 +39,7 @@ public class Day14_Tests
    {
        Day14 day = new();

-        string result = day.ResolvePart1(new[] { "2018", });
+        string result = day.ResolvePart1(["2018"]);

        Assert.Equal("5941429882", result);
    }
@@ -53,7 +53,7 @@ public class Day14_Tests
    {
        Day14 day = new();

-        string result = day.ResolvePart2(new[] { "51589", });
+        string result = day.ResolvePart2(["51589"]);

        Assert.Equal("9", result);
    }
@@ -63,7 +63,7 @@ public class Day14_Tests
    {
        Day14 day = new();

-        string result = day.ResolvePart2(new[] { "01245", });
+        string result = day.ResolvePart2(["01245"]);

        Assert.Equal("5", result);
    }
@@ -73,7 +73,7 @@ public class Day14_Tests
    {
        Day14 day = new();

-        string result = day.ResolvePart2(new[] { "92510", });
+        string result = day.ResolvePart2(["92510"]);

        Assert.Equal("18", result);
    }
@@ -83,7 +83,7 @@ public class Day14_Tests
    {
        Day14 day = new();

-        string result = day.ResolvePart2(new[] { "59414", });
+        string result = day.ResolvePart2(["59414"]);

        Assert.Equal("2018", result);
    }
--- a/AdventOfCode2018.Tests/Day15_Tests.cs
+++ b/AdventOfCode2018.Tests/Day15_Tests.cs
@@ -9,7 +9,7 @@ public class Day15_Tests
    {
        Day15 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "#######",
            "#.G...#",
            "#...EG#",
@@ -17,7 +17,7 @@ public class Day15_Tests
            "#..G#E#",
            "#.....#",
            "#######",
-        });
+        ]);

        Assert.Equal("27730", result);
    }
@@ -27,7 +27,7 @@ public class Day15_Tests
    {
        Day15 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "#######",
            "#G..#E#",
            "#E#E.E#",
@@ -35,7 +35,7 @@ public class Day15_Tests
            "#...#E#",
            "#...E.#",
            "#######",
-        });
+        ]);

        Assert.Equal("36334", result);
    }
@@ -45,7 +45,7 @@ public class Day15_Tests
    {
        Day15 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "#######",
            "#E..EG#",
            "#.#G.E#",
@@ -53,7 +53,7 @@ public class Day15_Tests
            "#G..#.#",
            "#..E#.#",
            "#######",
-        });
+        ]);

        Assert.Equal("39514", result);
    }
@@ -63,7 +63,7 @@ public class Day15_Tests
    {
        Day15 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "#######",
            "#E.G#.#",
            "#.#G..#",
@@ -71,7 +71,7 @@ public class Day15_Tests
            "#G..#.#",
            "#...E.#",
            "#######",
-        });
+        ]);

        Assert.Equal("27755", result);
    }
@@ -81,7 +81,7 @@ public class Day15_Tests
    {
        Day15 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "#######",
            "#.E...#",
            "#.#..G#",
@@ -89,7 +89,7 @@ public class Day15_Tests
            "#E#G#G#",
            "#...#G#",
            "#######",
-        });
+        ]);

        Assert.Equal("28944", result);
    }
@@ -99,7 +99,7 @@ public class Day15_Tests
    {
        Day15 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "#########",
            "#G......#",
            "#.E.#...#",
@@ -109,7 +109,7 @@ public class Day15_Tests
            "#.G...G.#",
            "#.....G.#",
            "#########",
-        });
+        ]);

        Assert.Equal("18740", result);
    }
@@ -123,7 +123,7 @@ public class Day15_Tests
    {
        Day15 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "#######",
            "#.G...#",
            "#...EG#",
@@ -131,7 +131,7 @@ public class Day15_Tests
            "#..G#E#",
            "#.....#",
            "#######",
-        });
+        ]);

        Assert.Equal("4988", result);
    }
@@ -141,7 +141,7 @@ public class Day15_Tests
    {
        Day15 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "#######",
            "#E..EG#",
            "#.#G.E#",
@@ -149,7 +149,7 @@ public class Day15_Tests
            "#G..#.#",
            "#..E#.#",
            "#######",
-        });
+        ]);

        Assert.Equal("31284", result);
    }
@@ -159,7 +159,7 @@ public class Day15_Tests
    {
        Day15 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "#######",
            "#E.G#.#",
            "#.#G..#",
@@ -167,7 +167,7 @@ public class Day15_Tests
            "#G..#.#",
            "#...E.#",
            "#######",
-        });
+        ]);

        Assert.Equal("3478", result);
    }
@@ -177,7 +177,7 @@ public class Day15_Tests
    {
        Day15 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "#######",
            "#.E...#",
            "#.#..G#",
@@ -185,7 +185,7 @@ public class Day15_Tests
            "#E#G#G#",
            "#...#G#",
            "#######",
-        });
+        ]);

        Assert.Equal("6474", result);
    }
@@ -195,7 +195,7 @@ public class Day15_Tests
    {
        Day15 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "#########",
            "#G......#",
            "#.E.#...#",
@@ -205,7 +205,7 @@ public class Day15_Tests
            "#.G...G.#",
            "#.....G.#",
            "#########",
-        });
+        ]);

        Assert.Equal("1140", result);
    }
--- a/AdventOfCode2018.Tests/Day16_Tests.cs
+++ b/AdventOfCode2018.Tests/Day16_Tests.cs
@@ -7,7 +7,7 @@ public class Day16_Tests
    {
        Day16 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "Before: [3, 2, 1, 1]",
            "9 2 1 2",
            "After:  [3, 2, 2, 1]",
@@ -18,7 +18,7 @@ public class Day16_Tests
            "",
            "",
            "Garbage",
-        });
+        ]);

        Assert.Equal("2", result);
    }
--- a/AdventOfCode2018.Tests/Day23_Tests.cs
+++ b/AdventOfCode2018.Tests/Day23_Tests.cs
@@ -7,7 +7,7 @@ public class Day23_Tests
    {
        Day23 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "pos=<0,0,0>, r=4",
            "pos=<1,0,0>, r=1",
            "pos=<4,0,0>, r=3",
@@ -17,7 +17,7 @@ public class Day23_Tests
            "pos=<1,1,1>, r=1",
            "pos=<1,1,2>, r=1",
            "pos=<1,3,1>, r=1",
-        });
+        ]);

        Assert.Equal("7", result);
    }
@@ -27,14 +27,14 @@ public class Day23_Tests
    {
        Day23 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "pos=<10,12,12>, r=2",
            "pos=<12,14,12>, r=2",
            "pos=<16,12,12>, r=4",
            "pos=<14,14,14>, r=6",
            "pos=<50,50,50>, r=200",
            "pos=<10,10,10>, r=5",
-        });
+        ]);

        Assert.Equal("36", result);
    }
--- a/AdventOfCode2018.Tests/packages.config
+++ b/AdventOfCode2018.Tests/packages.config
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
-  <package id="MSTest.TestAdapter" version="1.4.0" targetFramework="net461" />
-  <package id="MSTest.TestFramework" version="1.4.0" targetFramework="net461" />
+    <package id="MSTest.TestAdapter" version="1.4.0" targetFramework="net461"/>
+    <package id="MSTest.TestFramework" version="1.4.0" targetFramework="net461"/>
 </packages>
--- a/AdventOfCode2018/AdventOfCode2018.csproj
+++ b/AdventOfCode2018/AdventOfCode2018.csproj
@@ -2,8 +2,9 @@

    <PropertyGroup>
        <OutputType>Exe</OutputType>
-    <TargetFramework>net7.0</TargetFramework>
+        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
        <RootNamespace>AdventOfCode2018</RootNamespace>
    </PropertyGroup>

@@ -14,7 +15,7 @@
    </ItemGroup>

    <ItemGroup>
-    <ProjectReference Include="..\AdventOfCode.Common\AdventOfCode.Common.csproj" />
+        <ProjectReference Include="..\AdventOfCode.Common\AdventOfCode.Common.csproj"/>
    </ItemGroup>

 </Project>
--- a/AdventOfCode2018/Day01.cs
+++ b/AdventOfCode2018/Day01.cs
@@ -63,8 +63,7 @@ public class Day01 : IDay
        int accumulator = 0;
        foreach (string input in inputs)
        {
-            int intInput;
-            if (int.TryParse(input.Substring(1), out intInput))
+            if (int.TryParse(input.Substring(1), out int intInput))
            {
                if (input[0] == '-')
                {
@@ -83,15 +82,14 @@ public class Day01 : IDay
    public string ResolvePart2(string[] inputs)
    {
        int accumulator = 0;
-        List<int> accumulatorHistory = new();
+        List<int> accumulatorHistory = [];
        int? repeatedAccumulator = null;
        while (repeatedAccumulator == null)
        {
            foreach (string input in inputs)
            {
                accumulatorHistory.Add(accumulator);
-                int intInput;
-                if (int.TryParse(input.Substring(1), out intInput))
+                if (int.TryParse(input.Substring(1), out int intInput))
                {
                    if (input[0] == '-')
                    {
@@ -110,6 +108,6 @@ public class Day01 : IDay
                }
            }
        }
-        return repeatedAccumulator.ToString();
+        return repeatedAccumulator.ToString() ?? string.Empty;
    }
 }
--- a/AdventOfCode2018/Day02.cs
+++ b/AdventOfCode2018/Day02.cs
@@ -50,7 +50,7 @@ What letters are common between the two correct box IDs? (In the example above,

 public class Day02 : IDay
 {
-    private int CountOccurrencesOfLetter(string text, char letter)
+    private static int CountOccurrencesOfLetter(string text, char letter)
    {
        return text.Count(c => (c == letter));
    }
@@ -75,7 +75,7 @@ public class Day02 : IDay
        int tripletsCount = 0;
        foreach (string input in inputs)
        {
-            var hasPairsAndTriplets = HasPairsAndTriplets(input);
+            Tuple<bool, bool> hasPairsAndTriplets = HasPairsAndTriplets(input);
            if (hasPairsAndTriplets.Item1) { pairsCount++; }
            if (hasPairsAndTriplets.Item2) { tripletsCount++; }
        }
@@ -104,11 +104,10 @@ public class Day02 : IDay
        {
            for (int j = (i + 1); j < inputs.Length; j++)
            {
-                var result = CompareIDPair(inputs[i], inputs[j]);
+                Tuple<int, string> result = CompareIDPair(inputs[i], inputs[j]);
                if (result.Item1 == 1) { return result.Item2; }
            }
        }
        return string.Empty;
    }
-
 }
--- a/AdventOfCode2018/Day03.cs
+++ b/AdventOfCode2018/Day03.cs
@@ -60,7 +60,7 @@ public class Day03 : IDay
 {
    public string ResolvePart1(string[] inputs)
    {
-        List<Claim> claims = inputs.Select(i => Claim.FromString(i)).ToList();
+        List<Claim> claims = inputs.Select(Claim.FromString).ToList();

        const int edgeSize = 1000;
        int[,] cells = new int[edgeSize, edgeSize];
@@ -92,9 +92,9 @@ public class Day03 : IDay

    public string ResolvePart2(string[] inputs)
    {
-        List<Claim> claims = inputs.Select(i => Claim.FromString(i)).ToList();
+        List<Claim> claims = inputs.Select(Claim.FromString).ToList();

-        Claim unoverlappingClaim = null;
+        Claim? unOverlappingClaim = null;
        for (int i = 0; i < claims.Count; i++)
        {
            bool overlaps = false;
@@ -109,29 +109,43 @@ public class Day03 : IDay
            }
            if (overlaps == false)
            {
-                unoverlappingClaim = claims[i];
+                unOverlappingClaim = claims[i];
                break;
            }
        }
-        return unoverlappingClaim.ID.ToString();
+        return unOverlappingClaim?.ID.ToString() ?? string.Empty;

    }

    public class Claim
    {
-        public int ID { get; set; }
+        public int ID { get; private set; }

-        public int Left { get; set; }
-        public int Top { get; set; }
+        public int Left { get; private set; }
+        public int Top { get; private set; }

-        public int Width { get; set; }
-        public int Height { get; set; }
+        public int Width { get; private set; }
+        public int Height { get; private set; }

-        public int MinX { get { return Left; } }
-        public int MaxX { get { return Left + Width; } }
+        private int MinX
+        {
+            get { return Left; }
+        }

-        public int MinY { get { return Top; } }
-        public int MaxY { get { return Top + Height; } }
+        private int MaxX
+        {
+            get { return Left + Width; }
+        }
+
+        private int MinY
+        {
+            get { return Top; }
+        }
+
+        private int MaxY
+        {
+            get { return Top + Height; }
+        }

        public int GetArea()
        {
@@ -141,7 +155,7 @@ public class Day03 : IDay
        public static Claim FromString(string strClaim)
        {
            Claim claim = new();
-            string[] parts = strClaim.Split(new[] { " @ ", ",", ": ", "x", }, StringSplitOptions.None);
+            string[] parts = strClaim.Split([" @ ", ",", ": ", "x"], StringSplitOptions.None);
            claim.ID = Convert.ToInt32(parts[0].Substring(1));
            claim.Left = Convert.ToInt32(parts[1]);
            claim.Top = Convert.ToInt32(parts[2]);
--- a/AdventOfCode2018/Day04.cs
+++ b/AdventOfCode2018/Day04.cs
@@ -68,14 +68,14 @@ public class Day04 : IDay
    public string ResolvePart1(string[] inputs)
    {
        List<GuardEvent> guardEvents = GuardEvent.FromStringArray(inputs);
-        Dictionary<int, GuardSleepHistogram> dictFullHistogram = BuildFullHistorgram(guardEvents);
+        Dictionary<int, GuardSleepHistogram> dictFullHistogram = BuildFullHistogram(guardEvents);

        // Find sleepier guard
-        GuardSleepHistogram highestSleeperHistogram = null;
+        GuardSleepHistogram? highestSleeperHistogram = null;
        long highestTotalSleep = long.MinValue;
        foreach (GuardSleepHistogram guardHistogram in dictFullHistogram.Values)
        {
-            int totalSleep = guardHistogram.SleepOnMunute.Sum();
+            int totalSleep = guardHistogram.SleepOnMinute.Sum();

            if (totalSleep > highestTotalSleep)
            {
@@ -83,16 +83,17 @@ public class Day04 : IDay
                highestTotalSleep = totalSleep;
            }
        }
+        if (highestSleeperHistogram == null) { return string.Empty; }

        // Find sleepier minute
        int maxSleepMinute = int.MinValue;
        int maxSleepMinuteValue = int.MinValue;
        for (int i = 0; i < GuardSleepHistogram.MinutesOnHour; i++)
        {
-            if (highestSleeperHistogram.SleepOnMunute[i] > maxSleepMinuteValue)
+            if (highestSleeperHistogram.SleepOnMinute[i] > maxSleepMinuteValue)
            {
                maxSleepMinute = i;
-                maxSleepMinuteValue = highestSleeperHistogram.SleepOnMunute[i];
+                maxSleepMinuteValue = highestSleeperHistogram.SleepOnMinute[i];
            }
        }

@@ -103,7 +104,7 @@ public class Day04 : IDay
    public string ResolvePart2(string[] inputs)
    {
        List<GuardEvent> guardEvents = GuardEvent.FromStringArray(inputs);
-        Dictionary<int, GuardSleepHistogram> dictFullHistogram = BuildFullHistorgram(guardEvents);
+        Dictionary<int, GuardSleepHistogram> dictFullHistogram = BuildFullHistogram(guardEvents);

        int selectedGuardID = int.MinValue;
        int selectedMinute = int.MinValue;
@@ -112,9 +113,9 @@ public class Day04 : IDay
        {
            foreach (GuardSleepHistogram guardHistogram in dictFullHistogram.Values)
            {
-                if (guardHistogram.SleepOnMunute[i] > maxSleepMinuteValue)
+                if (guardHistogram.SleepOnMinute[i] > maxSleepMinuteValue)
                {
-                    maxSleepMinuteValue = guardHistogram.SleepOnMunute[i];
+                    maxSleepMinuteValue = guardHistogram.SleepOnMinute[i];
                    selectedGuardID = guardHistogram.ID;
                    selectedMinute = i;
                }
@@ -125,7 +126,7 @@ public class Day04 : IDay
        return result.ToString();
    }

-    private static Dictionary<int, GuardSleepHistogram> BuildFullHistorgram(List<GuardEvent> guardEvents)
+    private static Dictionary<int, GuardSleepHistogram> BuildFullHistogram(List<GuardEvent> guardEvents)
    {
        Dictionary<int, GuardSleepHistogram> dictFullHistogram = new();
        foreach (IGrouping<int, GuardEvent> group in guardEvents.GroupBy(guardEvent => guardEvent.Date.DayOfYear))
@@ -156,18 +157,14 @@ public class Day04 : IDay

            foreach (GuardSleepHistogram dayGuardHistogram in dictDayHistogram.Values)
            {
-                GuardSleepHistogram guardHistogram;
-                if (dictFullHistogram.ContainsKey(dayGuardHistogram.ID))
+                if (dictFullHistogram.TryGetValue(dayGuardHistogram.ID, out GuardSleepHistogram? guardHistogram))
                {
-                    guardHistogram = dictFullHistogram[dayGuardHistogram.ID];
                    guardHistogram.AddHistogram(dayGuardHistogram);
+                    continue;
                }
-                else
-                {
                dictFullHistogram.Add(dayGuardHistogram.ID, dayGuardHistogram);
            }
        }
-        }

        return dictFullHistogram;
    }
@@ -181,14 +178,14 @@ public class Day04 : IDay

    public class GuardEvent
    {
-        public DateTime Date { get; set; }
-        public int? ID { get; set; }
-        public GuardEventType Type { get; set; }
+        public DateTime Date { get; private set; }
+        public int? ID { get; private set; }
+        public GuardEventType Type { get; private set; }

        public static GuardEvent FromString(string strEvent)
        {
            GuardEvent guardEvent = new();
-            string[] parts = strEvent.Split(new[] { "[", "-", " ", ":", "]", "#", }, StringSplitOptions.RemoveEmptyEntries);
+            string[] parts = strEvent.Split(["[", "-", " ", ":", "]", "#"], StringSplitOptions.RemoveEmptyEntries);
            guardEvent.Date = new DateTime(
                Convert.ToInt32(parts[0]),
                Convert.ToInt32(parts[1]),
@@ -216,7 +213,7 @@ public class Day04 : IDay
        public static List<GuardEvent> FromStringArray(string[] strEvents)
        {
            List<GuardEvent> guardEvents = strEvents
-                .Select(strEvent => FromString(strEvent))
+                .Select(FromString)
                .OrderBy(guardEvent => guardEvent.Date)
                .ToList();

@@ -240,14 +237,14 @@ public class Day04 : IDay
    public class GuardSleepHistogram
    {
        public const int MinutesOnHour = 60;
-        public int ID { get; set; }
-        public int[] SleepOnMunute { get; } = new int[MinutesOnHour];
+        public int ID { get; init; }
+        public int[] SleepOnMinute { get; } = new int[MinutesOnHour];

        public void FallSleep(int minute)
        {
            for (int i = minute; i < MinutesOnHour; i++)
            {
-                SleepOnMunute[i] = 1;
+                SleepOnMinute[i] = 1;
            }
        }

@@ -255,7 +252,7 @@ public class Day04 : IDay
        {
            for (int i = minute; i < MinutesOnHour; i++)
            {
-                SleepOnMunute[i] = 0;
+                SleepOnMinute[i] = 0;
            }
        }

@@ -263,7 +260,7 @@ public class Day04 : IDay
        {
            for (int i = 0; i < MinutesOnHour; i++)
            {
-                SleepOnMunute[i] += histogram.SleepOnMunute[i];
+                SleepOnMinute[i] += histogram.SleepOnMinute[i];
            }
        }
    }
--- a/AdventOfCode2018/Day05.cs
+++ b/AdventOfCode2018/Day05.cs
@@ -108,7 +108,7 @@ public class Day05 : IDay
    public string ResolvePart2(string[] inputs)
    {
        string input = inputs[0];
-        List<char> allUnitTypes = input.Select(c => char.ToLower(c)).Distinct().ToList();
+        List<char> allUnitTypes = input.Select(char.ToLower).Distinct().ToList();

        int minPolymerLenght = int.MaxValue;
        foreach (char unitType in allUnitTypes)
--- a/AdventOfCode2018/Day06.cs
+++ b/AdventOfCode2018/Day06.cs
@@ -96,7 +96,8 @@ public class Day06 : IDay
    {
        return inputs
            .Where(input => string.IsNullOrEmpty(input) == false)
-            .Select(input => ChronoPoint.FromString(input))
+            .Select(ChronoPoint.FromString)
+            .OfType<ChronoPoint>()
            .ToList();
    }

@@ -183,12 +184,12 @@ public class Day06 : IDay
        return areaInRange;
    }

-    public int DistanceThresold { get; set; } = 10000;
+    public int DistanceThreshold { get; init; } = 10000;

    public string ResolvePart2(string[] inputs)
    {
        List<ChronoPoint> points = InputsToPoints(inputs);
-        int areaInRange = AreaInThresold(points, DistanceThresold);
+        int areaInRange = AreaInThresold(points, DistanceThreshold);
        return areaInRange.ToString();
    }

@@ -197,10 +198,10 @@ public class Day06 : IDay
        public int X { get; set; }
        public int Y { get; set; }

-        public static ChronoPoint FromString(string strPoint)
+        public static ChronoPoint? FromString(string strPoint)
        {
            if (string.IsNullOrEmpty(strPoint)) { return null; }
-            string[] parts = strPoint.Split(new[] { ", ", }, StringSplitOptions.RemoveEmptyEntries);
+            string[] parts = strPoint.Split([", "], StringSplitOptions.RemoveEmptyEntries);
            if (parts.Length < 2) { return null; }
            ChronoPoint point = new() {
                X = Convert.ToInt32(parts[0]),
--- a/AdventOfCode2018/Day07.cs
+++ b/AdventOfCode2018/Day07.cs
@@ -89,11 +89,11 @@ public class Day07 : IDay
        foreach (string input in inputs)
        {
            if (string.IsNullOrEmpty(input)) { continue; }
-            string[] parts = input.Split(new[] {
+            string[] parts = input.Split([
                "Step ",
                " must be finished before step ",
                " can begin.",
-            }, StringSplitOptions.RemoveEmptyEntries);
+            ], StringSplitOptions.RemoveEmptyEntries);
            instructions.AddNodeRelation(parts[1].ToUpper(), parts[0].ToUpper());
        }
        foreach (InstructionNode node in instructions.Nodes.Values)
@@ -118,8 +118,8 @@ public class Day07 : IDay
        return sbInstructions.ToString();
    }

-    public int BaseCost { get; set; } = 60;
-    public int NumberOfWorkers { get; set; } = 5;
+    public int BaseCost { get; init; } = 60;
+    public int NumberOfWorkers { get; init; } = 5;

    public string ResolvePart2(string[] inputs)
    {
@@ -128,11 +128,11 @@ public class Day07 : IDay
        return totalElapsedTime.ToString();
    }

-    public class InstructionNode
+    public class InstructionNode(string nodeID)
    {
-        public string NodeID { get; set; }
+        public string NodeID { get; init; } = nodeID;

-        public List<string> PreviousNodeIDs { get; } = new();
+        public List<string> PreviousNodeIDs { get; } = [];

        public int Cost { get; set; }

@@ -148,22 +148,18 @@ public class Day07 : IDay
        }
    }

-    public class Instructions
+    private class Instructions
    {
        public Dictionary<string, InstructionNode> Nodes { get; } = new();

-        public InstructionNode GetNode(string nodeID)
+        private InstructionNode GetNode(string nodeID)
        {
-            InstructionNode node = null;
-            if (Nodes.ContainsKey(nodeID))
+            if (Nodes.TryGetValue(nodeID, out InstructionNode? nodeAux))
            {
-                node = Nodes[nodeID];
+                return nodeAux;
            }
-            else
-            {
-                node = new InstructionNode { NodeID = nodeID, };
+            InstructionNode node = new(nodeID);
            Nodes.Add(nodeID, node);
-            }
            return node;
        }

@@ -176,7 +172,7 @@ public class Day07 : IDay

        public List<InstructionNode> SortInstructions()
        {
-            List<InstructionNode> finalNodes = new();
+            List<InstructionNode> finalNodes = [];

            foreach (InstructionNode node in Nodes.Values)
            {
@@ -194,7 +190,8 @@ public class Day07 : IDay
                    .ToList();
                if (unusedNodes.Count > 0)
                {
-                    InstructionNode node = unusedNodes.FirstOrDefault();
+                    InstructionNode? node = unusedNodes.FirstOrDefault();
+                    if (node == null) { continue; }
                    finalNodes.Add(node);
                    node.Used = true;
                }
@@ -204,8 +201,8 @@ public class Day07 : IDay

        private class SimulatedWorker
        {
-            public InstructionNode CurrentInstruction { get; set; }
-            public int ElapsedTime { get; set; }
+            public InstructionNode? CurrentInstruction { get; private set; }
+            private int ElapsedTime { get; set; }

            public void SetInstruction(InstructionNode instruction)
            {
@@ -242,7 +239,6 @@ public class Day07 : IDay
                workers.Add(new SimulatedWorker());
            }

-            bool anyWorkerWitoutWork;
            do
            {
                bool anyWorkDone = false;
@@ -255,8 +251,8 @@ public class Day07 : IDay
                }
                if (anyWorkDone) { totalElapsedTime++; }

-                anyWorkerWitoutWork = workers.Any(w => w.CurrentInstruction == null);
-                if (anyWorkerWitoutWork)
+                bool anyWorkerWithoutWork = workers.Any(w => w.CurrentInstruction == null);
+                if (anyWorkerWithoutWork)
                {
                    List<InstructionNode> unusedNodes = Nodes.Values
                        .Where(n =>
--- a/AdventOfCode2018/Day08.cs
+++ b/AdventOfCode2018/Day08.cs
@@ -77,13 +77,13 @@ public class Day08 : IDay

    public class IntStream
    {
-        private int[] _values;
+        private readonly int[] _values;
        private int _index;

        public IntStream(string strValues)
        {
            _values = strValues
-                .Split(new[] { " ", }, StringSplitOptions.RemoveEmptyEntries)
+                .Split([" "], StringSplitOptions.RemoveEmptyEntries)
                .Select(strVal => Convert.ToInt32(strVal))
                .ToArray();
            _index = 0;
@@ -99,9 +99,9 @@ public class Day08 : IDay

    public class ChronoLicenceNode
    {
-        public List<ChronoLicenceNode> Childs { get; } = new();
+        public List<ChronoLicenceNode> Childs { get; } = [];

-        public List<int> Metadata { get; } = new();
+        public List<int> Metadata { get; } = [];

        public static ChronoLicenceNode BuildFromIntStream(IntStream stream)
        {
--- a/AdventOfCode2018/Day09.cs
+++ b/AdventOfCode2018/Day09.cs
@@ -75,7 +75,7 @@ public class Day09 : IDay

    private static string CalculateHighScore(string input, long factor)
    {
-        string[] parts = input.Split(new[] { " players; last marble is worth ", " points" }, StringSplitOptions.RemoveEmptyEntries);
+        string[] parts = input.Split([" players; last marble is worth ", " points"], StringSplitOptions.RemoveEmptyEntries);
        long numberOfPlayers = Convert.ToInt32(parts[0]);
        long lastMarble = Convert.ToInt32(parts[1]) * factor;
        MarbleGame marbleGame = new();
@@ -86,17 +86,17 @@ public class Day09 : IDay

    public class Marble
    {
-        public long Value { get; set; }
-        public Marble Previous { get; set; }
-        public Marble Next { get; set; }
+        public long Value { get; init; }
+        public Marble? Previous { get; set; }
+        public Marble? Next { get; set; }
    }

    public class MarbleGame
    {
-        public Dictionary<long, long> Scores { get; } = new();
+        private Dictionary<long, long> Scores { get; } = new();

-        private Marble _firstMarble;
-        private Marble _currentMarble;
+        private Marble? _firstMarble;
+        private Marble? _currentMarble;
        private long _currentPlayer;

        private const long PointValueMultiple = 23;
@@ -119,20 +119,34 @@ public class Day09 : IDay
                Marble newMarble = new() { Value = i + 1 };
                if ((newMarble.Value % PointValueMultiple) > 0)
                {
-                    Marble previousMarble = _currentMarble.Next;
-                    Marble nextMarble = previousMarble.Next;
+                    Marble? previousMarble = _currentMarble?.Next;
+                    Marble? nextMarble = previousMarble?.Next;
                    newMarble.Previous = previousMarble;
                    newMarble.Next = nextMarble;
+                    if(previousMarble != null)
+                    {
                        previousMarble.Next = newMarble;
+                    }
+                    if(nextMarble != null)
+                    {
                        nextMarble.Previous = newMarble;
+                    }
                    _currentMarble = newMarble;
                }
                else
                {
-                    Marble marbleToRemove = _currentMarble.Previous.Previous.Previous.Previous.Previous.Previous.Previous;
-                    _currentMarble = marbleToRemove.Next;
+                    Marble? marbleToRemove = _currentMarble?.Previous?.Previous?.Previous?.Previous?.Previous?.Previous?.Previous;
+                    _currentMarble = marbleToRemove?.Next;
+                    if (marbleToRemove == null) { continue; }
+                    
+                    if(marbleToRemove.Previous != null)
+                    {
                        marbleToRemove.Previous.Next = marbleToRemove.Next;
+                    }
+                    if (marbleToRemove.Next != null)
+                    {
                        marbleToRemove.Next.Previous = marbleToRemove.Previous;
+                    }

                    long currentPlayerScore = Scores[_currentPlayer] + (newMarble.Value + marbleToRemove.Value);
                    Scores[_currentPlayer] = currentPlayerScore;
@@ -141,22 +155,17 @@ public class Day09 : IDay
            }
        }

-        public void PrintStatus()
+        private void PrintStatus()
        {
            Console.Write("[{0}] ", _currentPlayer);
-            Marble marble = _firstMarble;
+            Marble? marble = _firstMarble;
            do
            {
-                if (_currentMarble.Value == marble.Value)
-                {
-                    Console.Write("({0}) ", marble.Value);
-                }
-                else
-                {
-                    Console.Write("{0} ", marble.Value);
-                }
-                marble = marble.Next;
-            } while (marble.Value != 0);
+                Console.Write(_currentMarble?.Value == marble?.Value 
+                    ? "({0}) " 
+                    : "{0} ", marble?.Value);
+                marble = marble?.Next;
+            } while (marble != null && marble.Value != 0);
            Console.WriteLine();
        }

--- a/AdventOfCode2018/Day10.cs
+++ b/AdventOfCode2018/Day10.cs
@@ -156,13 +156,13 @@ Impressed by your sub-hour communication capabilities, the Elves are curious: ex

 public class Day10 : IDay
 {
-    public int Width { get; set; } = 65;
-    public int Height { get; set; } = 12;
+    public int Width { get; init; } = 65;
+    public int Height { get; init; } = 12;

    public string ResolvePart1(string[] inputs)
    {
        LightField lightField = new(inputs);
-        int t = lightField.SearchSmallerBoundindBox();
+        int t = lightField.SearchSmallerBoundingBox();
        string result = lightField.Render(t, Width, Height);
        return result;
    }
@@ -170,20 +170,20 @@ public class Day10 : IDay
    public string ResolvePart2(string[] inputs)
    {
        LightField lightField = new(inputs);
-        int t = lightField.SearchSmallerBoundindBox();
+        int t = lightField.SearchSmallerBoundingBox();
        return t.ToString();
    }

    public class LightPoint
    {
-        public int X { get; set; }
-        public int Y { get; set; }
-        public int VX { get; set; }
-        public int VY { get; set; }
+        private int X { get; init; }
+        private int Y { get; init; }
+        private int VX { get; init; }
+        private int VY { get; init; }

        public static LightPoint FromString(string strPoint)
        {
-            string[] parts = strPoint.Split(new[] { "position=<", " ", ",", "> velocity=<", ">" }, StringSplitOptions.RemoveEmptyEntries);
+            string[] parts = strPoint.Split(["position=<", " ", ",", "> velocity=<", ">"], StringSplitOptions.RemoveEmptyEntries);
            LightPoint point = new() {
                X = Convert.ToInt32(parts[0]),
                Y = Convert.ToInt32(parts[1]),
@@ -204,16 +204,11 @@ public class Day10 : IDay
        }
    }

-    public class LightField
+    private class LightField(string[] strPoints)
    {
-        private readonly List<LightPoint> _points;
+        private readonly List<LightPoint> _points = strPoints.Select(LightPoint.FromString).ToList();

-        public LightField(string[] strPoints)
-        {
-            _points = strPoints.Select(strPoint => LightPoint.FromString(strPoint)).ToList();
-        }
-
-        public int SearchSmallerBoundindBox()
+        public int SearchSmallerBoundingBox()
        {
            int minHeight = int.MaxValue;
            int minT = 0;
@@ -288,14 +283,7 @@ public class Day10 : IDay
                sb.AppendLine();
                for (int i = 0; i < width; i++)
                {
-                    if (field[i, j] > 0)
-                    {
-                        sb.Append("#");
-                    }
-                    else
-                    {
-                        sb.Append(".");
-                    }
+                    sb.Append(field[i, j] > 0 ? "#" : ".");
                }
            }
            return sb.ToString();
--- a/AdventOfCode2018/Day11.cs
+++ b/AdventOfCode2018/Day11.cs
@@ -190,7 +190,7 @@ public class Day11 : IDay
        return powerLevel;
    }

-    public static void SearchBestRegion(int width, int height, int serial, out int x, out int y, out int size)
+    private static void SearchBestRegion(int width, int height, int serial, out int x, out int y, out int size)
    {
        int[,] summationFiled = GenerateSumationField(width, height, serial);
        int bestPowerLevel = int.MinValue;
--- a/AdventOfCode2018/Day12.cs
+++ b/AdventOfCode2018/Day12.cs
@@ -96,23 +96,23 @@ public class Day12 : IDay

    private class PlantRule
    {
-        public bool Minus2 { get; set; }
-        public bool Minus1 { get; set; }
-        public bool Current { get; set; }
-        public bool Plus1 { get; set; }
-        public bool Plus2 { get; set; }
+        public bool Minus2 { get; init; }
+        public bool Minus1 { get; init; }
+        public bool Current { get; init; }
+        public bool Plus1 { get; init; }
+        public bool Plus2 { get; init; }

-        public bool Result { get; set; }
+        public bool Result { get; init; }
    }

    private const int SideMargin = 5;
    private const int SideProcessMargin = 2;

-    private List<bool> _initialState = new();
-    private List<PlantRule> _rules = new();
+    private readonly List<bool> _initialState = [];
+    private readonly List<PlantRule> _rules = [];
    private long _offsetField;
-    private bool[] _field;
-    private bool[] _workField;
+    private bool[] _field = [];
+    private bool[] _workField = [];

    private void Initialize(string[] inputs)
    {
@@ -126,9 +126,8 @@ public class Day12 : IDay
        for (int i = 2; i < inputs.Length; i++)
        {
            if (string.IsNullOrEmpty(inputs[i])) { continue; }
-            string[] parts = inputs[i].Split(new[] { " => " }, StringSplitOptions.RemoveEmptyEntries);
-            _rules.Add(new PlantRule
-            {
+            string[] parts = inputs[i].Split([" => "], StringSplitOptions.RemoveEmptyEntries);
+            _rules.Add(new PlantRule {
                Minus2 = (parts[0][0] == '#'),
                Minus1 = (parts[0][1] == '#'),
                Current = (parts[0][2] == '#'),
@@ -151,9 +150,7 @@ public class Day12 : IDay

    private void SwapFields()
    {
-        bool[] aux = _field;
-        _field = _workField;
-        _workField = aux;
+        (_field, _workField) = (_workField, _field);
    }

    private void RecenterField()
@@ -236,8 +233,7 @@ public class Day12 : IDay
                    rule.Minus1 == minus1 &&
                    rule.Current == current &&
                    rule.Plus1 == plus1 &&
-                    rule.Plus2 == plus2 &&
-                    true
+                    rule.Plus2 == plus2
                )
                {
                    result = rule.Result;
--- a/AdventOfCode2018/Day13.cs
+++ b/AdventOfCode2018/Day13.cs
@@ -217,7 +217,7 @@ public class Day13 : IDay
    public string ResolvePart1(string[] inputs)
    {
        Initialize(inputs);
-        Train collidingTrain;
+        Train? collidingTrain;
        do
        {
            if (ShowProgress) { ShowGrid(); }
@@ -229,7 +229,7 @@ public class Day13 : IDay
    public string ResolvePart2(string[] inputs)
    {
        Initialize(inputs);
-        Train lastCart;
+        Train? lastCart;
        do
        {
            if (ShowProgress) { ShowGrid(); }
@@ -371,8 +371,8 @@ public class Day13 : IDay

    private int _width;
    private int _height;
-    private char[,] _grid;
-    private List<Train> _trains = new();
+    private char[,] _grid = new char[0, 0];
+    private readonly List<Train> _trains = [];

    private void Initialize(string[] inputs)
    {
@@ -387,8 +387,7 @@ public class Day13 : IDay
                char cell = inputs[j][i];
                if (cell == '^')
                {
-                    _trains.Add(new Train
-                    {
+                    _trains.Add(new Train {
                        X = i,
                        Y = j,
                        Direction = TrainDirection.North,
@@ -398,8 +397,7 @@ public class Day13 : IDay
                }
                if (cell == 'v')
                {
-                    _trains.Add(new Train
-                    {
+                    _trains.Add(new Train {
                        X = i,
                        Y = j,
                        Direction = TrainDirection.South,
@@ -409,8 +407,7 @@ public class Day13 : IDay
                }
                if (cell == '<')
                {
-                    _trains.Add(new Train
-                    {
+                    _trains.Add(new Train {
                        X = i,
                        Y = j,
                        Direction = TrainDirection.West,
@@ -420,8 +417,7 @@ public class Day13 : IDay
                }
                if (cell == '>')
                {
-                    _trains.Add(new Train
-                    {
+                    _trains.Add(new Train {
                        X = i,
                        Y = j,
                        Direction = TrainDirection.East,
@@ -434,9 +430,9 @@ public class Day13 : IDay
        }
    }

-    private Train SimulateForFirstCollision()
+    private Train? SimulateForFirstCollision()
    {
-        Train collidingTrain = null;
+        Train? collidingTrain = null;
        IEnumerable<Train> orderedTrains = _trains.OrderBy(t => t.X + (t.Y * _width));
        foreach (Train t in orderedTrains)
        {
@@ -447,13 +443,13 @@ public class Day13 : IDay
        return collidingTrain;
    }

-    private Train SimulateForLastCart()
+    private Train? SimulateForLastCart()
    {
        List<Train> orderedTrains = _trains.OrderBy(t => t.X + (t.Y * _width)).ToList();
        foreach (Train t in orderedTrains)
        {
            t.Simulate(_grid);
-            Train collidingTrain = _trains.FirstOrDefault(x => x.X == t.X && x.Y == t.Y && t != x);
+            Train? collidingTrain = _trains.FirstOrDefault(x => x.X == t.X && x.Y == t.Y && t != x);
            if (collidingTrain != null)
            {
                _trains.Remove(t);
@@ -474,7 +470,7 @@ public class Day13 : IDay
        {
            for (int i = 0; i < _width; i++)
            {
-                Train t = _trains.FirstOrDefault(x => x.X == i && x.Y == j);
+                Train? t = _trains.FirstOrDefault(x => x.X == i && x.Y == j);
                if (t != null)
                {
                    if (t.Direction == TrainDirection.North)
@@ -502,5 +498,4 @@ public class Day13 : IDay
            Console.WriteLine();
        }
    }
-
 }
--- a/AdventOfCode2018/Day14.cs
+++ b/AdventOfCode2018/Day14.cs
@@ -62,7 +62,7 @@ public class Day14 : IDay
 {
    private long _numRecipes;
    private long _numRecipesAllocated;
-    private byte[] _recipes;
+    private byte[] _recipes = [];
    private long _idxA;
    private long _idxB;
    private long _searchSkip;
--- a/AdventOfCode2018/Day15.cs
+++ b/AdventOfCode2018/Day15.cs
@@ -377,18 +377,18 @@ public class Day15 : IDay
 {
    public enum EntityType { Elf, Goblin, }

-    public bool Show { get; set; } = false;
+    private bool Show { get; set; } = false;

    public class Entity
    {
-        public const int GoblinAttackPower = 3;
+        private const int GoblinAttackPower = 3;
        public static int ElfAttackPower { get; set; } = 3;
-        public const int InitialHealth = 200;
+        private const int InitialHealth = 200;

-        public EntityType Type { get; set; }
+        public EntityType Type { get; init; }
        public int X { get; set; }
        public int Y { get; set; }
-        public int Health { get; set; } = InitialHealth;
+        public int Health { get; private set; } = InitialHealth;

        public bool IsAlive()
        {
@@ -401,8 +401,7 @@ public class Day15 : IDay
                (other.X + 1 == X && other.Y == Y) ||
                (other.X - 1 == X && other.Y == Y) ||
                (other.X == X && other.Y + 1 == Y) ||
-                (other.X == X && other.Y - 1 == Y) ||
-                false
+                (other.X == X && other.Y - 1 == Y)
            )
            {
                return true;
@@ -412,7 +411,7 @@ public class Day15 : IDay

        public void Attack(char[,] map, Entity other)
        {
-            if(Type == EntityType.Elf)
+            if (Type == EntityType.Elf)
            {
                other.Health -= ElfAttackPower;
            }
@@ -435,20 +434,19 @@ public class Day15 : IDay
        }
    }

-    public class Target
+    private class Target
    {
-        public int X { get; set; }
-        public int Y { get; set; }
+        public int X { get; init; }
+        public int Y { get; init; }
        public int Distance { get; set; }
-        public int Priority { get; set; }
-        public Entity Entity { get; set; }
+        public int Priority { get; init; }
    }

    private int _width;
    private int _height;
-    private char[,] _map;
-    private List<Entity> _entities;
-    private BreadthFirstSearchGrid _search;
+    private char[,] _map = new char[0, 0];
+    private readonly List<Entity> _entities = [];
+    private BreadthFirstSearchGrid? _search;
    private int _rounds;

    private void Init(string[] inputs)
@@ -456,7 +454,7 @@ public class Day15 : IDay
        _height = inputs.Length;
        _width = inputs.Max(input => input.Length);
        _map = new char[_width, _height];
-        _entities = new List<Entity>();
+        _entities.Clear();
        for (int j = 0; j < _height; j++)
        {
            for (int i = 0; i < _width; i++)
@@ -473,8 +471,7 @@ public class Day15 : IDay
                }
                else if (cell == 'E')
                {
-                    _entities.Add(new Entity
-                    {
+                    _entities.Add(new Entity {
                        Type = EntityType.Elf,
                        X = i,
                        Y = j,
@@ -483,8 +480,7 @@ public class Day15 : IDay
                }
                else if (cell == 'G')
                {
-                    _entities.Add(new Entity
-                    {
+                    _entities.Add(new Entity {
                        Type = EntityType.Goblin,
                        X = i,
                        Y = j,
@@ -505,7 +501,7 @@ public class Day15 : IDay
            .ThenBy(e => e.X);
    }

-    public IEnumerable<Entity> GetTargetEntities(Entity entity)
+    private IEnumerable<Entity> GetTargetEntities(Entity entity)
    {
        return _entities
            .Where(e => e.IsAlive() && e.Type != entity.Type)
@@ -513,30 +509,29 @@ public class Day15 : IDay
            .ThenBy(e => e.X);
    }

-    public Entity GetBestInRangeTarget(Entity entity, IEnumerable<Entity> targets)
+    private Entity? GetBestInRangeTarget(Entity entity, IEnumerable<Entity> targets)
    {
        return targets
-            .Where(e => entity.InRangeOf(e))
+            .Where(entity.InRangeOf)
            .OrderBy(e => e.Health)
            .ThenBy(e => e.Y)
            .ThenBy(e => e.X)
            .FirstOrDefault();
    }

-    private void AddTarget(List<Target> targets, int targetX, int targetY, int priority, Entity entity)
+    private void AddTarget(List<Target> targets, int targetX, int targetY, int priority)
    {
+        if (_search == null) { return;}
        if (targetX >= 0 && targetX < _width && targetY >= 0 && targetY < _height && _map[targetX, targetY] == '.')
        {
            int distance = _search.QueryDistance(targetX, targetY);
            if (distance >= 0)
            {
-                targets.Add(new Target
-                {
+                targets.Add(new Target {
                    X = targetX,
                    Y = targetY,
                    Distance = distance,
                    Priority = priority,
-                    Entity = entity,
                });
            }
        }
@@ -544,6 +539,7 @@ public class Day15 : IDay

    private void RunBattle()
    {
+        if (_search == null) { return;}
        _rounds = 0;
        bool running = true;
        do
@@ -552,7 +548,7 @@ public class Day15 : IDay
            foreach (Entity entity in entities)
            {
                if (entity.IsAlive() == false) { continue; }
-                IEnumerable<Entity> entitiesTargets = GetTargetEntities(entity);
+                IEnumerable<Entity> entitiesTargets = GetTargetEntities(entity).ToList();
                if (entitiesTargets.Any() == false)
                {
                    running = false;
@@ -560,7 +556,7 @@ public class Day15 : IDay
                }

                // Attack
-                Entity targetInRange = GetBestInRangeTarget(entity, entitiesTargets);
+                Entity? targetInRange = GetBestInRangeTarget(entity, entitiesTargets);
                if (targetInRange != null)
                {
                    entity.Attack(_map, targetInRange);
@@ -573,19 +569,18 @@ public class Day15 : IDay
                int priority = 0;
                foreach (Entity entityTarget in entitiesTargets)
                {
-                    AddTarget(targets, entityTarget.X, entityTarget.Y - 1, priority++, entityTarget);
-                    AddTarget(targets, entityTarget.X - 1, entityTarget.Y, priority++, entityTarget);
-                    AddTarget(targets, entityTarget.X + 1, entityTarget.Y, priority++, entityTarget);
-                    AddTarget(targets, entityTarget.X, entityTarget.Y + 1, priority++, entityTarget);
+                    AddTarget(targets, entityTarget.X, entityTarget.Y - 1, priority++);
+                    AddTarget(targets, entityTarget.X - 1, entityTarget.Y, priority++);
+                    AddTarget(targets, entityTarget.X + 1, entityTarget.Y, priority++);
+                    AddTarget(targets, entityTarget.X, entityTarget.Y + 1, priority++);
                }
-                Target bestTarget = targets.OrderBy(t => t.Distance).ThenBy(t => t.Priority).FirstOrDefault();
+                Target? bestTarget = targets.OrderBy(t => t.Distance).ThenBy(t => t.Priority).FirstOrDefault();
                if (bestTarget != null)
                {
                    _search.SearchCharGrid(_map, '.', bestTarget.X, bestTarget.Y);
                    targets.Clear();
-                    Target dirTarget;

-                    dirTarget = new Target { X = entity.X, Y = entity.Y - 1, Priority = 0, };
+                    Target dirTarget = new() { X = entity.X, Y = entity.Y - 1, Priority = 0, };
                    dirTarget.Distance = _search.QueryDistance(dirTarget.X, dirTarget.Y);
                    if (dirTarget.Distance >= 0) targets.Add(dirTarget);

@@ -601,7 +596,7 @@ public class Day15 : IDay
                    dirTarget.Distance = _search.QueryDistance(dirTarget.X, dirTarget.Y);
                    if (dirTarget.Distance >= 0) targets.Add(dirTarget);

-                    Target finalTarget = targets
+                    Target? finalTarget = targets
                        .OrderBy(t => t.Distance)
                        .ThenBy(t => t.Priority)
                        .FirstOrDefault();
@@ -613,17 +608,17 @@ public class Day15 : IDay
                    entity.MoveTo(_map, finalTarget.X, finalTarget.Y);

                    // Attack
-                    Entity targetInRangeAfterMove = GetBestInRangeTarget(entity, entitiesTargets);
+                    Entity? targetInRangeAfterMove = GetBestInRangeTarget(entity, entitiesTargets);
                    if (targetInRangeAfterMove != null)
                    {
                        entity.Attack(_map, targetInRangeAfterMove);
                    }
                }
            }
-            if(running == false) { break; }
+            if (running == false) { break; }
            _rounds++;
            if (Show) { PrintBattlefield(); }
-        } while (running);
+        } while (true);
        if (Show) { PrintBattlefield(); }
    }

@@ -637,7 +632,8 @@ public class Day15 : IDay
            {
                Console.Write(_map[i, j]);
            }
-            IEnumerable<Entity> entitiesOnLine = _entities.Where(e => e.IsAlive() && e.Y == j).OrderBy(e => e.X);
+            int j1 = j;
+            IEnumerable<Entity> entitiesOnLine = _entities.Where(e => e.IsAlive() && e.Y == j1).OrderBy(e => e.X);
            foreach (Entity entity in entitiesOnLine)
            {
                Console.Write(" {0}({1})", (entity.Type == EntityType.Elf) ? 'E' : 'G', entity.Health);
@@ -683,10 +679,9 @@ public class Day15 : IDay
        private class BFSCell
        {
            public bool Visited { get; set; }
-            public BFSCell CameFrom { get; set; }
            public int Distance { get; set; } = -1;
-            public int X { get; set; }
-            public int Y { get; set; }
+            public int X { get; init; }
+            public int Y { get; init; }
        }

        private readonly BFSCell[,] _grid;
@@ -707,24 +702,23 @@ public class Day15 : IDay
            }
        }

-        public void Reset()
+        private void Reset()
        {
-            for(int j =0;j< _height; j++)
+            for (int j = 0; j < _height; j++)
            {
-                for(int i = 0; i < _width; i++)
+                for (int i = 0; i < _width; i++)
                {
                    BFSCell cell = _grid[i, j];
                    cell.Visited = false;
-                    cell.CameFrom = null;
                    cell.Distance = -1;
                }
            }
        }

-        private void ProcessCell(char[,] grid, char empty, Queue<BFSCell> frontier, BFSCell current, int nextX, int nextY)
+        private void ProcessCell(char[,] grid, char empty, Queue<BFSCell> frontier, BFSCell? current, int nextX, int nextY)
        {
            if (nextX < 0 || nextX >= _width || nextY < 0 || nextY >= _height) { return; }
-            if (grid[nextX, nextY] == empty || current== null)
+            if (grid[nextX, nextY] == empty || current == null)
            {
                BFSCell cell = _grid[nextX, nextY];
                if (cell.Visited == false)
@@ -732,7 +726,6 @@ public class Day15 : IDay
                    frontier.Enqueue(cell);
                    cell.Visited = true;
                    cell.Distance = (current?.Distance ?? -1) + 1;
-                    cell.CameFrom = current;
                }
            }
        }
--- a/AdventOfCode2018/Day16.cs
+++ b/AdventOfCode2018/Day16.cs
@@ -87,8 +87,8 @@ public class Day16 : IDay
        int count = 0;
        int i = 0;
        bool end = false;
-        int[] beforeRegisters = null;
-        int[] instruction = null;
+        int[]? beforeRegisters = null;
+        int[]? instruction = null;
        const string beforeKeyword = "Before: [";
        const string afterKeyword = "After:  [";
        while (inputs.Length > i)
@@ -160,17 +160,11 @@ public class Day16 : IDay

        private readonly List<ChronoInstruction> _instructions;

-        private class ChronoInstruction
+        private class ChronoInstruction(string opName, Action<int, int, int> opFunc)
        {
            public int OpCode { get; set; } = -1;
-            public string OpName { get; }
-            public Action<int, int, int> OpFunc { get; }
-
-            public ChronoInstruction(string opName, Action<int, int, int> opFunc)
-            {
-                OpName = opName;
-                OpFunc = opFunc;
-            }
+            public string OpName { get; } = opName;
+            public Action<int, int, int> OpFunc { get; } = opFunc;

            public Dictionary<int, int> OpCodeHistogram { get; } = new();

@@ -191,7 +185,7 @@ public class Day16 : IDay
        public ChronoMachine()
        {
            _registers = new int[4];
-            _instructions = new List<ChronoInstruction> {
+            _instructions = [
                new("addr", Op_AddR),
                new("addi", Op_AddI),
                new("mulr", Op_MulR),
@@ -208,7 +202,7 @@ public class Day16 : IDay
                new("eqir", Op_EqIR),
                new("eqri", Op_EqRI),
                new("eqrr", Op_EqRR),
-            };
+            ];
        }

        public void ResetRegisters()
@@ -341,7 +335,7 @@ public class Day16 : IDay

        public void InitOpCodes(bool debug = false)
        {
-            if(debug)
+            if (debug)
            {
                foreach (ChronoInstruction instruction in _instructions)
                {
@@ -374,7 +368,7 @@ public class Day16 : IDay

                    instruction.OpCode = opCode;
                    _dictInstructions.Add(opCode, instruction);
-                    if(debug) { Console.WriteLine($"{instruction.OpName}: {instruction.OpCode}"); }
+                    if (debug) { Console.WriteLine($"{instruction.OpName}: {instruction.OpCode}"); }
                }
            }
        }
--- a/AdventOfCode2018/Day23.cs
+++ b/AdventOfCode2018/Day23.cs
@@ -68,8 +68,8 @@ public class Day23 : IDay
    public string ResolvePart1(string[] inputs)
    {
        List<NanoBot> nanoBots = NanoBot.ListFromStrings(inputs);
-        NanoBot bestNanoBot = nanoBots.OrderBy(nanoBot => nanoBot.Range).LastOrDefault();
-        int countInRange = nanoBots.Where(nanoBot => bestNanoBot.InRange(nanoBot)).Count();
+        NanoBot? bestNanoBot = nanoBots.OrderBy(nanoBot => nanoBot.Range).LastOrDefault();
+        int countInRange = nanoBots.Count(nanoBot => bestNanoBot?.InRange(nanoBot) == true);
        return countInRange.ToString();
    }

@@ -82,7 +82,7 @@ public class Day23 : IDay
        long minX = long.MaxValue;
        long minY = long.MaxValue;
        long minZ = long.MaxValue;
-        foreach(NanoBot nanoBot in nanoBots)
+        foreach (NanoBot nanoBot in nanoBots)
        {
            if (nanoBot.X < minX) { minX = nanoBot.X; }
            if (nanoBot.X > maxX) { maxX = nanoBot.X; }
@@ -112,11 +112,11 @@ public class Day23 : IDay
                    for (long i = minX; i <= maxX; i += scale)
                    {
                        int count = 0;
-                        foreach(NanoBot nanoBot in nanoBots)
+                        foreach (NanoBot nanoBot in nanoBots)
                        {
                            if (nanoBot.InRange(i, j, k, scale)) { count++; }
                        }
-                        if(count> bestCount)
+                        if (count > bestCount)
                        {
                            bestX = i;
                            bestY = j;
@@ -134,7 +134,7 @@ public class Day23 : IDay
            minZ = bestZ - scale;
            maxZ = bestZ + scale;

-            if(scale == 1)
+            if (scale == 1)
            {
                long distance = bestX + bestY + bestZ;
                return distance.ToString();
@@ -145,14 +145,14 @@ public class Day23 : IDay

    public class NanoBot
    {
-        public long X { get; set; }
-        public long Y { get; set; }
-        public long Z { get; set; }
-        public long Range { get; set; }
+        public long X { get; private init; }
+        public long Y { get; private init; }
+        public long Z { get; private init; }
+        public long Range { get; private init; }

-        public static NanoBot FromString(string strInput)
+        private static NanoBot? FromString(string strInput)
        {
-            string[] parts = strInput.Split(new[] { "pos=<", ",", ">, r=", }, StringSplitOptions.RemoveEmptyEntries);
+            string[] parts = strInput.Split(["pos=<", ",", ">, r="], StringSplitOptions.RemoveEmptyEntries);
            if (parts.Length != 4) { return null; }
            NanoBot nanoBot = new() {
                X = Convert.ToInt64(parts[0]),
@@ -166,18 +166,18 @@ public class Day23 : IDay
        public static List<NanoBot> ListFromStrings(string[] inputs)
        {
            List<NanoBot> nanoBots = inputs
-                .Select(strInput => FromString(strInput))
-                .Where(nanoBot => nanoBot != null)
+                .Select(FromString)
+                .OfType<NanoBot>()
                .ToList();
            return nanoBots;
        }

-        public long ManhattanDistance(NanoBot other)
+        private long ManhattanDistance(NanoBot other)
        {
            return ManhattanDistance(other.X, other.Y, other.Z);
        }

-        public long ManhattanDistance(long x, long y, long z)
+        private long ManhattanDistance(long x, long y, long z)
        {
            long distance = Math.Abs(X - x) + Math.Abs(Y - y) + Math.Abs(Z - z);
            return distance;
--- a/AdventOfCode2020.Tests/AdventOfCode2020.Tests.csproj
+++ b/AdventOfCode2020.Tests/AdventOfCode2020.Tests.csproj
@@ -1,16 +1,18 @@
 <Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
-    <TargetFramework>net7.0</TargetFramework>
+        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
        <RootNamespace>AdventOfCode2020.Tests</RootNamespace>

        <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
    </PropertyGroup>

    <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-    <PackageReference Include="xunit" Version="2.6.3" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0"/>
+        <PackageReference Include="xunit" Version="2.6.3"/>
        <PackageReference Include="xunit.runner.visualstudio" Version="2.5.5">
            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
            <PrivateAssets>all</PrivateAssets>
@@ -18,7 +20,7 @@
    </ItemGroup>

    <ItemGroup>
-    <ProjectReference Include="..\AdventOfCode2020\AdventOfCode2020.csproj" />
+        <ProjectReference Include="..\AdventOfCode2020\AdventOfCode2020.csproj"/>
    </ItemGroup>

 </Project>
--- a/AdventOfCode2020.Tests/Day01_Tests.cs
+++ b/AdventOfCode2020.Tests/Day01_Tests.cs
@@ -7,16 +7,16 @@ public class Day01_Tests
    [Fact]
    public void ResolvePart1__Example()
    {
-        var day = new Day01();
+        Day01 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "1721",
            "979",
            "366",
            "299",
            "675",
            "1456",
-        });
+        ]);

        Assert.Equal("514579", result);
    }
@@ -28,16 +28,16 @@ public class Day01_Tests
    [Fact]
    public void ResolvePart2__Example()
    {
-        var day = new Day01();
+        Day01 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "1721",
            "979",
            "366",
            "299",
            "675",
            "1456",
-        });
+        ]);

        Assert.Equal("241861950", result);
    }
--- a/AdventOfCode2020.Tests/Day02_Tests.cs
+++ b/AdventOfCode2020.Tests/Day02_Tests.cs
@@ -7,13 +7,13 @@ public class Day02_Tests
    [Fact]
    public void ResolvePart1__Example()
    {
-        var day = new Day02();
+        Day02 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "1-3 a: abcde",
            "1-3 b: cdefg",
            "2-9 c: ccccccccc",
-        });
+        ]);

        Assert.Equal("2", result);
    }
@@ -25,13 +25,13 @@ public class Day02_Tests
    [Fact]
    public void ResolvePart2__Example()
    {
-        var day = new Day02();
+        Day02 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "1-3 a: abcde",
            "1-3 b: cdefg",
            "2-9 c: ccccccccc",
-        });
+        ]);

        Assert.Equal("1", result);
    }
--- a/AdventOfCode2020.Tests/Day03_Tests.cs
+++ b/AdventOfCode2020.Tests/Day03_Tests.cs
@@ -5,9 +5,9 @@ public class Day03_Tests
    [Fact]
    public void ResolvePart1__Example()
    {
-        var day = new Day03();
+        Day03 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "..##.......",
            "#...#...#..",
            ".#....#..#.",
@@ -19,7 +19,7 @@ public class Day03_Tests
            "#.##...#...",
            "#...##....#",
            ".#..#...#.#",
-        });
+        ]);

        Assert.Equal("7", result);
    }
@@ -27,9 +27,9 @@ public class Day03_Tests
    [Fact]
    public void ResolvePart2__Example()
    {
-        var day = new Day03();
+        Day03 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "..##.......",
            "#...#...#..",
            ".#....#..#.",
@@ -41,7 +41,7 @@ public class Day03_Tests
            "#.##...#...",
            "#...##....#",
            ".#..#...#.#",
-        });
+        ]);

        Assert.Equal("336", result);
    }
--- a/AdventOfCode2020.Tests/Day04_Tests.cs
+++ b/AdventOfCode2020.Tests/Day04_Tests.cs
@@ -5,9 +5,9 @@ public class Day04_Tests
    [Fact]
    public void ResolvePart1__Example()
    {
-        var day = new Day04();
+        Day04 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "ecl:gry pid:860033327 eyr:2020 hcl:#fffffd",
            "byr:1937 iyr:2017 cid:147 hgt:183cm",
            "",
@@ -21,7 +21,7 @@ public class Day04_Tests
            "",
            "hcl:#cfa07d eyr:2025 pid:166559648",
            "iyr:2011 ecl:brn hgt:59in",
-        });
+        ]);

        Assert.Equal("2", result);
    }
@@ -29,9 +29,9 @@ public class Day04_Tests
    [Fact]
    public void ResolvePart2__ExampleInvalid()
    {
-        var day = new Day04();
+        Day04 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "eyr:1972 cid:100",
            "hcl:#18171d ecl:amb hgt:170 pid:186cm iyr:2018 byr:1926",
            "",
@@ -45,7 +45,7 @@ public class Day04_Tests
            "hgt:59cm ecl:zzz",
            "eyr:2038 hcl:74454a iyr:2023",
            "pid:3556412378 byr:2007",
-        });
+        ]);

        Assert.Equal("0", result);
    }
@@ -53,9 +53,9 @@ public class Day04_Tests
    [Fact]
    public void ResolvePart2__ExampleValid()
    {
-        var day = new Day04();
+        Day04 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "pid:087499704 hgt:74in ecl:grn iyr:2012 eyr:2030 byr:1980",
            "hcl:#623a2f",
            "",
@@ -68,7 +68,7 @@ public class Day04_Tests
            "eyr:2022",
            "",
            "iyr:2010 hgt:158cm hcl:#b6652a ecl:blu byr:1944 eyr:2021 pid:093154719",
-        });
+        ]);

        Assert.Equal("4", result);
    }
--- a/AdventOfCode2020.Tests/Day05_Tests.cs
+++ b/AdventOfCode2020.Tests/Day05_Tests.cs
@@ -5,11 +5,11 @@ public class Day05_Tests
    [Fact]
    public void ResolvePart1__Example1()
    {
-        var day = new Day05();
+        Day05 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "FBFBBFFRLR",
-        });
+        ]);

        Assert.Equal("357", result);
    }
@@ -17,11 +17,11 @@ public class Day05_Tests
    [Fact]
    public void ResolvePart1__Example2()
    {
-        var day = new Day05();
+        Day05 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "BFFFBBFRRR",
-        });
+        ]);

        Assert.Equal("567", result);
    }
@@ -29,11 +29,11 @@ public class Day05_Tests
    [Fact]
    public void ResolvePart1__Example3()
    {
-        var day = new Day05();
+        Day05 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "FFFBBBFRRR",
-        });
+        ]);

        Assert.Equal("119", result);
    }
@@ -41,11 +41,11 @@ public class Day05_Tests
    [Fact]
    public void ResolvePart1__Example4()
    {
-        var day = new Day05();
+        Day05 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "BBFFBBFRLL",
-        });
+        ]);

        Assert.Equal("820", result);
    }
--- a/AdventOfCode2020.Tests/Day06_Tests.cs
+++ b/AdventOfCode2020.Tests/Day06_Tests.cs
@@ -5,9 +5,9 @@ public class Day06_Tests
    [Fact]
    public void ResolvePart1__Example()
    {
-        var day = new Day06();
+        Day06 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "abc",
            "",
            "a",
@@ -23,7 +23,7 @@ public class Day06_Tests
            "a",
            "",
            "b",
-        });
+        ]);

        Assert.Equal("11", result);
    }
@@ -31,9 +31,9 @@ public class Day06_Tests
    [Fact]
    public void ResolvePart2__Example()
    {
-        var day = new Day06();
+        Day06 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "abc",
            "",
            "a",
@@ -49,7 +49,7 @@ public class Day06_Tests
            "a",
            "",
            "b",
-        });
+        ]);

        Assert.Equal("6", result);
    }
--- a/AdventOfCode2020.Tests/Day07_Tests.cs
+++ b/AdventOfCode2020.Tests/Day07_Tests.cs
@@ -5,9 +5,9 @@ public class Day07_Tests
    [Fact]
    public void ResolvePart1__Example()
    {
-        var day = new Day07();
+        Day07 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "light red bags contain 1 bright white bag, 2 muted yellow bags.",
            "dark orange bags contain 3 bright white bags, 4 muted yellow bags.",
            "bright white bags contain 1 shiny gold bag.",
@@ -17,7 +17,7 @@ public class Day07_Tests
            "vibrant plum bags contain 5 faded blue bags, 6 dotted black bags.",
            "faded blue bags contain no other bags.",
            "dotted black bags contain no other bags.",
-        });
+        ]);

        Assert.Equal("4", result);
    }
@@ -25,9 +25,9 @@ public class Day07_Tests
    [Fact]
    public void ResolvePart2__Example()
    {
-        var day = new Day07();
+        Day07 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "shiny gold bags contain 2 dark red bags.",
            "dark red bags contain 2 dark orange bags.",
            "dark orange bags contain 2 dark yellow bags.",
@@ -35,7 +35,7 @@ public class Day07_Tests
            "dark green bags contain 2 dark blue bags.",
            "dark blue bags contain 2 dark violet bags.",
            "dark violet bags contain no other bags.",
-        });
+        ]);

        Assert.Equal("126", result);
    }
--- a/AdventOfCode2020.Tests/Day08_Tests.cs
+++ b/AdventOfCode2020.Tests/Day08_Tests.cs
@@ -5,9 +5,9 @@ public class Day08_Tests
    [Fact]
    public void ResolvePart1__Example()
    {
-        var day = new Day08();
+        Day08 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "nop +0",
            "acc +1",
            "jmp +4",
@@ -17,7 +17,7 @@ public class Day08_Tests
            "acc +1",
            "jmp -4",
            "acc +6",
-        });
+        ]);

        Assert.Equal("5", result);
    }
@@ -25,9 +25,9 @@ public class Day08_Tests
    [Fact]
    public void ResolvePart2__Example()
    {
-        var day = new Day08();
+        Day08 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "nop +0",
            "acc +1",
            "jmp +4",
@@ -37,7 +37,7 @@ public class Day08_Tests
            "acc +1",
            "jmp -4",
            "acc +6",
-        });
+        ]);

        Assert.Equal("8", result);
    }
--- a/AdventOfCode2020.Tests/Day09_Tests.cs
+++ b/AdventOfCode2020.Tests/Day09_Tests.cs
@@ -5,9 +5,9 @@ public class Day09_Tests
    [Fact]
    public void ResolvePart1__Example()
    {
-        var day = new Day09();
+        Day09 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "35",
            "20",
            "15",
@@ -28,7 +28,7 @@ public class Day09_Tests
            "277",
            "309",
            "576",
-        });
+        ]);

        Assert.Equal("127", result);
    }
@@ -36,9 +36,9 @@ public class Day09_Tests
    [Fact]
    public void ResolvePart2__Example()
    {
-        var day = new Day09();
+        Day09 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "35",
            "20",
            "15",
@@ -59,7 +59,7 @@ public class Day09_Tests
            "277",
            "309",
            "576",
-        });
+        ]);

        Assert.Equal("62", result);
    }
--- a/AdventOfCode2020/AdventOfCode2020.csproj
+++ b/AdventOfCode2020/AdventOfCode2020.csproj
@@ -2,8 +2,9 @@

    <PropertyGroup>
        <OutputType>Exe</OutputType>
-    <TargetFramework>net7.0</TargetFramework>
+        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
        <RootNamespace>AdventOfCode2020</RootNamespace>
    </PropertyGroup>

@@ -14,7 +15,7 @@
    </ItemGroup>

    <ItemGroup>
-    <ProjectReference Include="..\AdventOfCode.Common\AdventOfCode.Common.csproj" />
+        <ProjectReference Include="..\AdventOfCode.Common\AdventOfCode.Common.csproj"/>
    </ItemGroup>

 </Project>
--- a/AdventOfCode2020/Day03.cs
+++ b/AdventOfCode2020/Day03.cs
@@ -112,5 +112,4 @@ public class Day03 : IDay
        }
        return treeCnt;
    }
-
 }
--- a/AdventOfCode2020/Day04.cs
+++ b/AdventOfCode2020/Day04.cs
@@ -127,7 +127,7 @@ public class Day04 : IDay
    {
        List<Dictionary<string, string>> passports = Passports_Parse(inputs);
        int cnt = 0;
-        List<string> neededFields = new() {
+        List<string> neededFields = [
            "byr", // Birth Year
            "iyr", // Issue Year
            "eyr", // Expiration Year
@@ -135,7 +135,7 @@ public class Day04 : IDay
            "hcl", // Hair Color
            "ecl", // Eye Color
            "pid", // Passport ID
-        };
+        ];

        foreach (Dictionary<string, string> passport in passports)
        {
@@ -167,7 +167,7 @@ public class Day04 : IDay

    private List<Dictionary<string, string>> Passports_Parse(string[] inputs)
    {
-        List<Dictionary<string, string>> passports = new();
+        List<Dictionary<string, string>> passports = [];
        Dictionary<string, string> passport = new();
        foreach (string input in inputs)
        {
@@ -257,5 +257,4 @@ public class Day04 : IDay
        if (input.All(char.IsNumber) == false) { return null; }
        return Convert.ToInt32(input);
    }
-
 }
--- a/AdventOfCode2020/Day05.cs
+++ b/AdventOfCode2020/Day05.cs
@@ -64,7 +64,7 @@ public class Day05 : IDay
        int maxSerialNumber = 0;
        foreach (string input in inputs)
        {
-            Seat seat = Seat_Parse(input);
+            Seat? seat = Seat_Parse(input);
            if (seat == null) { continue; }
            int newSerialNumber = seat.GetSerialNumber();
            if (newSerialNumber > maxSerialNumber) { maxSerialNumber = newSerialNumber; }
@@ -83,7 +83,7 @@ public class Day05 : IDay
        }
        foreach (string input in inputs)
        {
-            Seat seat = Seat_Parse(input);
+            Seat? seat = Seat_Parse(input);
            if (seat == null) { continue; }

            seats[seat.Column][seat.Row] = 'X';
@@ -166,11 +166,11 @@ public class Day05 : IDay
        }
    }

-    private Seat Seat_Parse(string input)
+    private Seat? Seat_Parse(string input)
    {
        if (input.Length != 10 ||
-            input.All(c => c == 'F' || c == 'B' || c == 'L' || c == 'R') == false ||
-            false)
+            input.All(c => c == 'F' || c == 'B' || c == 'L' || c == 'R') == false
+           )
        {
            return null;
        }
--- a/AdventOfCode2020/Day06.cs
+++ b/AdventOfCode2020/Day06.cs
@@ -67,10 +67,7 @@ public class Day06 : IDay

            foreach (char c in input)
            {
-                if (groupMap.ContainsKey(c) == false)
-                {
-                    groupMap.Add(c, true);
-                }
+                groupMap.TryAdd(c, true);
            }
        }
        if (groupMap.Count > 0)
@@ -78,7 +75,7 @@ public class Day06 : IDay
            groupMaps.Add(groupMap);
        }

-        int total = groupMaps.Sum(groupMap => groupMap.Count);
+        int total = groupMaps.Sum(dict => dict.Count);
        return total.ToString();

    }
@@ -101,13 +98,9 @@ public class Day06 : IDay
            groupCount++;
            foreach (char c in input)
            {
-                if (groupMap.ContainsKey(c) == false)
+                if (groupMap.TryAdd(c, 1) == false)
                {
-                    groupMap.Add(c, 1);
-                }
-                else
-                {
-                    groupMap[c] = groupMap[c] + 1;
+                    groupMap[c] += 1;
                }
            }
        }
--- a/AdventOfCode2020/Day07.cs
+++ b/AdventOfCode2020/Day07.cs
@@ -72,15 +72,15 @@ public class Day07 : IDay
    {
        string myBagColor = "shiny gold";

-        List<BaggageRule> rules = new();
+        List<BaggageRule> rules = [];
        foreach (string input in inputs)
        {
            BaggageRule rule = BaggageRule_Parse(input);
            rules.Add(rule);
        }

-        List<string> bagColorsToCheck = new() { myBagColor };
-        List<string> bagColorsChecked = new() { myBagColor };
+        List<string> bagColorsToCheck = [myBagColor];
+        List<string> bagColorsChecked = [myBagColor];
        int cntBagColors = 0;
        while (bagColorsToCheck.Count > 0)
        {
@@ -108,7 +108,7 @@ public class Day07 : IDay
    {
        string myBagColor = "shiny gold";

-        List<BaggageRule> rules = new();
+        List<BaggageRule> rules = [];
        foreach (string input in inputs)
        {
            BaggageRule rule = BaggageRule_Parse(input);
@@ -116,31 +116,30 @@ public class Day07 : IDay
        }
        Dictionary<string, BaggageRule> dictRules = rules.ToDictionary(x => x.BagColor);

-        int cnt = BaggageRule_CountChilds(myBagColor, dictRules);
+        int cnt = BaggageRule_CountChildren(myBagColor, dictRules);

        return cnt.ToString();
    }

-    public class BaggageContainRule
+    private class BaggageContainRule
    {
-        public string BagColor { get; set; }
-        public int Count { get; set; }
+        public string BagColor { get; set; } = string.Empty;
+        public int Count { get; init; }
    }

-    public class BaggageRule
+    private class BaggageRule
    {
-        public string BagColor { get; set; }
+        public string BagColor { get; set; } = string.Empty;

-        public List<BaggageContainRule> Contain { get; set; }
+        public List<BaggageContainRule> Contain { get; } = [];
    }

-    public BaggageRule BaggageRule_Parse(string input)
+    private BaggageRule BaggageRule_Parse(string input)
    {
        string[] words = input.Split(' ');
        string status = "Parse Color 1";
        BaggageRule rule = new();
-        rule.Contain = new List<BaggageContainRule>();
-        BaggageContainRule containRule = null;
+        BaggageContainRule? containRule = null;
        string color1 = string.Empty;

        foreach (string word in words)
@@ -164,9 +163,14 @@ public class Day07 : IDay
                    status = "Parse Contain count";
                    break;
                case "Parse Contain count":
-                    if (word == "no") { status = "End"; break; }
-                    containRule = new BaggageContainRule();
-                    containRule.Count = Convert.ToInt32(word);
+                    if (word == "no")
+                    {
+                        status = "End";
+                        break;
+                    }
+                    containRule = new BaggageContainRule {
+                        Count = Convert.ToInt32(word),
+                    };
                    status = "Parse Contain color 1";
                    break;
                case "Parse Contain color 1":
@@ -174,12 +178,17 @@ public class Day07 : IDay
                    status = "Parse Contain color 2";
                    break;
                case "Parse Contain color 2":
+                    if(containRule == null) { break; } 
                    containRule.BagColor = string.Concat(color1, " ", word);
                    rule.Contain.Add(containRule);
                    status = "Parse Contain continue";
                    break;
                case "Parse Contain continue":
-                    if (word == "bag," || word == "bags,") { status = "Parse Contain count"; break; }
+                    if (word == "bag," || word == "bags,")
+                    {
+                        status = "Parse Contain count";
+                        break;
+                    }
                    status = "End";
                    break;
                case "End":
@@ -189,13 +198,13 @@ public class Day07 : IDay
        return rule;
    }

-    public int BaggageRule_CountChilds(string color, Dictionary<string, BaggageRule> dictRules)
+    private int BaggageRule_CountChildren(string color, Dictionary<string, BaggageRule> dictRules)
    {
        int cnt = 0;
        BaggageRule rule = dictRules[color];
        foreach (BaggageContainRule containRule in rule.Contain)
        {
-            cnt += (BaggageRule_CountChilds(containRule.BagColor, dictRules) + 1) * containRule.Count;
+            cnt += (BaggageRule_CountChildren(containRule.BagColor, dictRules) + 1) * containRule.Count;
        }
        return cnt;
    }
--- a/AdventOfCode2020/Day08.cs
+++ b/AdventOfCode2020/Day08.cs
@@ -124,14 +124,14 @@ public class Day08 : IDay
        return vm.Accumulator.ToString();
    }

-    public enum OpCode
+    private enum OpCode
    {
        Acc,
        Jmp,
        Nop,
    }

-    public class Instruction
+    private class Instruction
    {
        public OpCode OpCode { get; set; }
        public int Value { get; set; }
@@ -154,14 +154,9 @@ public class Day08 : IDay
                OpCode = OpCode.Nop;
            }

-            if (parts[1].StartsWith("+"))
-            {
-                Value = Convert.ToInt32(parts[1].Substring(1));
-            }
-            else
-            {
-                Value = Convert.ToInt32(parts[1]);
-            }
+            Value = Convert.ToInt32(parts[1].StartsWith("+") 
+                ? parts[1].Substring(1) 
+                : parts[1]);
            Executed = false;
        }
    }
@@ -176,7 +171,7 @@ public class Day08 : IDay

        public VM(string[] inputs)
        {
-            Instructions = new List<Instruction>();
+            Instructions = [];
            foreach (string input in inputs)
            {
                Instructions.Add(new Instruction(input));
--- a/AdventOfCode2020/Day09.cs
+++ b/AdventOfCode2020/Day09.cs
@@ -163,5 +163,4 @@ public class Day09 : IDay

        return firstInvalid;
    }
-
 }
--- a/AdventOfCode2023.Tests/AdventOfCode2023.Tests.csproj
+++ b/AdventOfCode2023.Tests/AdventOfCode2023.Tests.csproj
@@ -1,17 +1,18 @@
 <Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
-        <TargetFramework>net7.0</TargetFramework>
+        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
-        <RootNamespace>AdventOfCode2023.Tests</RootNamespace>
        <Nullable>enable</Nullable>
+        <RootNamespace>AdventOfCode2023.Tests</RootNamespace>

        <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
    </PropertyGroup>

    <ItemGroup>
-        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-        <PackageReference Include="xunit" Version="2.6.3" />
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0"/>
+        <PackageReference Include="xunit" Version="2.6.3"/>
        <PackageReference Include="xunit.runner.visualstudio" Version="2.5.5">
            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
            <PrivateAssets>all</PrivateAssets>
@@ -19,7 +20,7 @@
    </ItemGroup>

    <ItemGroup>
-      <ProjectReference Include="..\AdventOfCode2023\AdventOfCode2023.csproj" />
+        <ProjectReference Include="..\AdventOfCode2023\AdventOfCode2023.csproj"/>
    </ItemGroup>

 </Project>
--- a/AdventOfCode2023.Tests/Day01_Tests.cs
+++ b/AdventOfCode2023.Tests/Day01_Tests.cs
@@ -5,14 +5,14 @@ public class Day01_Tests
    [Fact]
    public void ResolvePart1__Example()
    {
-        var day = new Day01();
+        Day01 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "1abc2",
            "pqr3stu8vwx",
            "a1b2c3d4e5f",
            "treb7uchet",
-        });
+        ]);

        Assert.Equal("142", result);
    }
@@ -20,9 +20,9 @@ public class Day01_Tests
    [Fact]
    public void ResolvePart2__Example()
    {
-        var day = new Day01();
+        Day01 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "two1nine",
            "eightwothree",
            "abcone2threexyz",
@@ -30,7 +30,7 @@ public class Day01_Tests
            "4nineeightseven2",
            "zoneight234",
            "7pqrstsixteen",
-        });
+        ]);

        Assert.Equal("281", result);
    }
--- a/AdventOfCode2023.Tests/Day02_Tests.cs
+++ b/AdventOfCode2023.Tests/Day02_Tests.cs
@@ -41,13 +41,13 @@ public class Day02_Tests
    {
        Day02 day = new();

-        string result = day.ResolvePart1(new[] {
+        string result = day.ResolvePart1([
            "Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green",
            "Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue",
            "Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red",
            "Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red",
            "Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green",
-        });
+        ]);

        Assert.Equal("8", result);
    }
@@ -57,13 +57,13 @@ public class Day02_Tests
    {
        Day02 day = new();

-        string result = day.ResolvePart2(new[] {
+        string result = day.ResolvePart2([
            "Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green",
            "Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue",
            "Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red",
            "Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red",
            "Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green",
-        });
+        ]);

        Assert.Equal("2286", result);
    }
--- a/AdventOfCode2023.Tests/Day03_Tests.cs
+++ b/AdventOfCode2023.Tests/Day03_Tests.cs
@@ -5,11 +5,11 @@ public class Day03_Tests
    [Fact]
    public void SearchNextSchemaNumber__NoNumbers__Null()
    {
-        string[] inputs = new[] {
+        string[] inputs = [
            "..........",
            "..........",
            "..........",
-        };
+        ];
        Day03.SchemaNumber? number = Day03.SearchNextSchemaNumber(inputs, 0, 0);

        Assert.Null(number);
@@ -18,11 +18,11 @@ public class Day03_Tests
    [Fact]
    public void SearchNextSchemaNumber__OneNumber__Valid()
    {
-        string[] inputs = new[] {
+        string[] inputs = [
            "..........",
            "....420...",
            "..........",
-        };
+        ];
        Day03.SchemaNumber? number = Day03.SearchNextSchemaNumber(inputs, 0, 0);

        Assert.NotNull(number);
@@ -35,11 +35,11 @@ public class Day03_Tests
    [Fact]
    public void SearchNextSchemaNumber__TwoNumbersSkipFirst__ValidSecond()
    {
-        string[] inputs = new[] {
+        string[] inputs = [
            "69........",
            "....420...",
            "..........",
-        };
+        ];
        Day03.SchemaNumber? number = Day03.SearchNextSchemaNumber(inputs, 0, 4);

        Assert.NotNull(number);
@@ -49,7 +49,7 @@ public class Day03_Tests
        Assert.Equal(420, number.Value.Value);
    }

-    private string[] _example = new[] {
+    private string[] _example = [
        "467..114..",
        "...*......",
        "..35..633.",
@@ -60,7 +60,7 @@ public class Day03_Tests
        "......755.",
        "...$.*....",
        ".664.598..",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example()
--- a/AdventOfCode2023.Tests/Day04_Tests.cs
+++ b/AdventOfCode2023.Tests/Day04_Tests.cs
@@ -2,14 +2,14 @@ namespace AdventOfCode2023.Tests;

 public class Day04_Tests
 {
-    private readonly string[] _example = {
+    private readonly string[] _example = [
        "Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53",
        "Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19",
        "Card 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1",
        "Card 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83",
        "Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36",
        "Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example()
--- a/AdventOfCode2023.Tests/Day05_Tests.cs
+++ b/AdventOfCode2023.Tests/Day05_Tests.cs
@@ -2,7 +2,7 @@ namespace AdventOfCode2023.Tests;

 public class Day05_Tests
 {
-    private readonly string[] _example = {
+    private readonly string[] _example = [
        "seeds: 79 14 55 13",
        "",
        "seed-to-soil map:",
@@ -36,7 +36,7 @@ public class Day05_Tests
        "humidity-to-location map:",
        "60 56 37",
        "56 93 4",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example()
@@ -61,7 +61,7 @@ public class Day05_Tests
    [Fact]
    public void AlmanacMapping_ParseNext__Empty__Null()
    {
-        Day05.LinesReader reader = new(Array.Empty<string>());
+        Day05.LinesReader reader = new([]);
        Day05.AlmanacMapping? mapping = Day05.AlmanacMapping.ParseNext(reader);

        Assert.Null(mapping);
@@ -70,11 +70,11 @@ public class Day05_Tests
    [Fact]
    public void AlmanacMapping_ParseNext__Example1()
    {
-        Day05.LinesReader reader = new(new[] { 
+        Day05.LinesReader reader = new([
            "seed-to-soil map:",
            "50 98 2",
            "52 50 48",
-        });
+        ]);
        Day05.AlmanacMapping? mapping = Day05.AlmanacMapping.ParseNext(reader);

        Assert.NotNull(mapping);
--- a/AdventOfCode2023.Tests/Day06_Tests.cs
+++ b/AdventOfCode2023.Tests/Day06_Tests.cs
@@ -2,10 +2,10 @@ namespace AdventOfCode2023.Tests;

 public class Day06_Tests
 {
-    private readonly string[] _example = {
+    private readonly string[] _example = [
        "Time:      7  15   30",
        "Distance:  9  40  200",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example()
--- a/AdventOfCode2023.Tests/Day07_Tests.cs
+++ b/AdventOfCode2023.Tests/Day07_Tests.cs
@@ -2,13 +2,13 @@ namespace AdventOfCode2023.Tests;

 public class Day07_Tests
 {
-    private readonly string[] _example = {
+    private readonly string[] _example = [
        "32T3K 765",
        "T55J5 684",
        "KK677 28",
        "KTJJT 220",
        "QQQJA 483",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example()
--- a/AdventOfCode2023.Tests/Day08_Tests.cs
+++ b/AdventOfCode2023.Tests/Day08_Tests.cs
@@ -2,7 +2,7 @@ namespace AdventOfCode2023.Tests;

 public class Day08_Tests
 {
-    private readonly string[] _example1 = {
+    private readonly string[] _example1 = [
        "RL",
        "",
        "AAA = (BBB, CCC)",
@@ -12,7 +12,7 @@ public class Day08_Tests
        "EEE = (EEE, EEE)",
        "GGG = (GGG, GGG)",
        "ZZZ = (ZZZ, ZZZ)",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example1()
@@ -24,13 +24,13 @@ public class Day08_Tests
        Assert.Equal("2", result);
    }

-    private readonly string[] _example2 = {
+    private readonly string[] _example2 = [
        "LLR",
        "",
        "AAA = (BBB, BBB)",
        "BBB = (AAA, ZZZ)",
        "ZZZ = (ZZZ, ZZZ)",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example2()
@@ -42,7 +42,7 @@ public class Day08_Tests
        Assert.Equal("6", result);
    }

-    private readonly string[] _example3 = {
+    private readonly string[] _example3 = [
        "LR",
        "",
        "11A = (11B, XXX)",
@@ -53,7 +53,7 @@ public class Day08_Tests
        "22C = (22Z, 22Z)",
        "22Z = (22B, 22B)",
        "XXX = (XXX, XXX)",
-    };
+    ];

    [Fact]
    public void ResolvePart2__Example3()
@@ -64,5 +64,4 @@ public class Day08_Tests

        Assert.Equal("6", result);
    }
-
 }
--- a/AdventOfCode2023.Tests/Day09_Tests.cs
+++ b/AdventOfCode2023.Tests/Day09_Tests.cs
@@ -2,11 +2,11 @@ namespace AdventOfCode2023.Tests;

 public class Day09_Tests
 {
-    private readonly string[] _example = {
+    private readonly string[] _example = [
        "0 3 6 9 12 15",
        "1 3 6 10 15 21",
        "10 13 16 21 30 45",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example()
--- a/AdventOfCode2023.Tests/Day10_Tests.cs
+++ b/AdventOfCode2023.Tests/Day10_Tests.cs
@@ -2,13 +2,13 @@ namespace AdventOfCode2023.Tests;

 public class Day10_Tests
 {
-    private readonly string[] _example1 = {
+    private readonly string[] _example1 = [
        "7-F7-",
        ".FJ|7",
        "SJLL7",
        "|F--J",
        "LJ.LJ",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example1()
@@ -20,7 +20,7 @@ public class Day10_Tests
        Assert.Equal("8", result);
    }

-    private readonly string[] _example2 = {
+    private readonly string[] _example2 = [
        "...........",
        ".S-------7.",
        ".|F-----7|.",
@@ -30,7 +30,7 @@ public class Day10_Tests
        ".|..|.|..|.",
        ".L--J.L--J.",
        "...........",
-    };
+    ];

    [Fact]
    public void ResolvePart2__Example2()
@@ -43,7 +43,7 @@ public class Day10_Tests
    }


-    private readonly string[] _example3 = {
+    private readonly string[] _example3 = [
        "FF7FSF7F7F7F7F7F---7",
        "L|LJ||||||||||||F--J",
        "FL-7LJLJ||||||LJL-77",
@@ -54,7 +54,7 @@ public class Day10_Tests
        "7-L-JL7||F7|L7F-7F7|",
        "L.L7LFJ|||||FJL7||LJ",
        "L7JLJL-JLJLJL--JLJ.L",
-    };
+    ];

    [Fact]
    public void ResolvePart2__Example3()
--- a/AdventOfCode2023.Tests/Day11_Tests.cs
+++ b/AdventOfCode2023.Tests/Day11_Tests.cs
@@ -2,7 +2,7 @@ namespace AdventOfCode2023.Tests;

 public class Day11_Tests
 {
-    private readonly string[] _example1 = {
+    private readonly string[] _example1 = [
        "...#......",
        ".......#..",
        "#.........",
@@ -13,7 +13,7 @@ public class Day11_Tests
        "..........",
        ".......#..",
        "#...#.....",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example1()
@@ -24,5 +24,4 @@ public class Day11_Tests

        Assert.Equal("374", result);
    }
-
 }
--- a/AdventOfCode2023.Tests/Day12_Tests.cs
+++ b/AdventOfCode2023.Tests/Day12_Tests.cs
@@ -2,14 +2,14 @@ namespace AdventOfCode2023.Tests;

 public class Day12_Tests
 {
-    private readonly string[] _example1 = {
+    private readonly string[] _example1 = [
        "???.### 1,1,3",
        ".??..??...?##. 1,1,3",
        "?#?#?#?#?#?#?#? 1,3,1,6",
        "????.#...#... 4,1,1",
        "????.######..#####. 1,6,5",
        "?###???????? 3,2,1",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example1()
--- a/AdventOfCode2023.Tests/Day24_Tests.cs
+++ b/AdventOfCode2023.Tests/Day24_Tests.cs
@@ -10,13 +10,13 @@ namespace AdventOfCode2023.Tests;

 public class Day24_Tests
 {
-    private string[] _example1 = {
+    private string[] _example1 = [
        "19, 13, 30 @ -2,  1, -2",
        "18, 19, 22 @ -1, -1, -2",
        "20, 25, 34 @ -2, -2, -4",
        "12, 31, 28 @ -1, -2, -1",
        "20, 19, 15 @  1, -5, -3",
-    };
+    ];

    [Fact]
    public void ResolvePart1__Example1()
@@ -67,5 +67,4 @@ public class Day24_Tests
        (bool intersect_D_E, _, _, _) = hailD.Intersect2D(hailE);
        Assert.True(intersect_D_E);
    }
-
 }
--- a/AdventOfCode2023/AdventOfCode2023.csproj
+++ b/AdventOfCode2023/AdventOfCode2023.csproj
@@ -2,10 +2,10 @@

    <PropertyGroup>
        <OutputType>Exe</OutputType>
-        <TargetFramework>net7.0</TargetFramework>
+        <TargetFramework>net8.0</TargetFramework>
        <ImplicitUsings>enable</ImplicitUsings>
-        <RootNamespace>AdventOfCode2023</RootNamespace>
        <Nullable>enable</Nullable>
+        <RootNamespace>AdventOfCode2023</RootNamespace>
    </PropertyGroup>

    <ItemGroup>
@@ -15,7 +15,7 @@
    </ItemGroup>

    <ItemGroup>
-      <ProjectReference Include="..\AdventOfCode.Common\AdventOfCode.Common.csproj" />
+        <ProjectReference Include="..\AdventOfCode.Common\AdventOfCode.Common.csproj"/>
    </ItemGroup>

 </Project>
--- a/AdventOfCode2023/Day01.cs
+++ b/AdventOfCode2023/Day01.cs
@@ -78,7 +78,7 @@ public class Day01 : IDay

    public string ResolvePart2(string[] inputs)
    {
-        List<(string Text, int Value)> digits = new() {
+        List<(string Text, int Value)> digits = [
            ("1", 1),
            ("2", 2),
            ("3", 3),
@@ -97,7 +97,7 @@ public class Day01 : IDay
            ("seven", 7),
            ("eight", 8),
            ("nine", 9),
-        };
+        ];

        int sum = 0;
        foreach (string line in inputs)
--- a/AdventOfCode2023/Day03.cs
+++ b/AdventOfCode2023/Day03.cs
@@ -115,11 +115,11 @@ public class Day03 : IDay

    public struct SchemaNumber
    {
-        public string[] Schema { get; set; }
-        public int Row { get; set; }
-        public int Column { get; set; }
-        public int Lenght { get; set; }
-        public int Value { get; set; }
+        public string[] Schema { get; init; }
+        public int Row { get; init; }
+        public int Column { get; init; }
+        public int Lenght { get; init; }
+        public int Value { get; init; }
    }

    public static SchemaNumber? SearchNextSchemaNumber(string[] schema, int initialRow, int initialColumn)
@@ -191,5 +191,4 @@ public class Day03 : IDay

        return false;
    }
-
 }
--- a/AdventOfCode2023/Day04.cs
+++ b/AdventOfCode2023/Day04.cs
@@ -135,6 +135,5 @@ public class Day04 : IDay
        {
            return _myNumbers.Count(myNumber => _winningNumbers.Contains(myNumber));
        }
-        
    }
 }
--- a/AdventOfCode2023/Day05.cs
+++ b/AdventOfCode2023/Day05.cs
@@ -136,7 +136,7 @@ public class Day05 : IDay
        LinesReader reader = new(inputs);
        Almanac? almanac = Almanac.Parse(reader);
        int i = 0;
-        List<AlmanacRangeMapping> ranges = new();
+        List<AlmanacRangeMapping> ranges = [];
        while (almanac?.Seeds.Count > i)
        {
            long seed = almanac.Seeds[i];
@@ -155,21 +155,14 @@ public class Day05 : IDay
    }


-    public class LinesReader
+    public class LinesReader(string[] lines)
    {
-        private readonly string[] _lines;
        private int _index;

-        public LinesReader(string[] lines)
-        {
-            _lines = lines;
-            _index = 0;
-        }
-
        public string? GetLine()
        {
-            if (_index >= _lines.Length) { return null; }
-            string line = _lines[_index];
+            if (_index >= lines.Length) { return null; }
+            string line = lines[_index];
            _index++;
            return line;
        }
@@ -298,7 +291,7 @@ public class Day05 : IDay
    {
        public string Name { get; private init; } = string.Empty;

-        public List<AlmanacRangeMapping> RangeMappings { get; } = new();
+        public List<AlmanacRangeMapping> RangeMappings { get; } = [];

        public static AlmanacMapping? ParseNext(LinesReader reader)
        {
@@ -346,29 +339,32 @@ public class Day05 : IDay

        public List<AlmanacRangeMapping> Apply(AlmanacRangeMapping range)
        {
-            List<AlmanacRangeMapping> unMappedRanges = new() {
+            List<AlmanacRangeMapping> unMappedRanges = [
                range,
-            };
-            List<AlmanacRangeMapping> newUnMappedRanges = new();
-            List<AlmanacRangeMapping> mappedRanges = new();
+            ];
+            List<AlmanacRangeMapping> newUnMappedRanges = [];
+            List<AlmanacRangeMapping> mappedRanges = [];

            int i = 0;
            while (RangeMappings.Count > i)
            {
                AlmanacRangeMapping rangeMapping = RangeMappings[i];
-                for (int j = 0; j < unMappedRanges.Count; j++)
+                foreach (AlmanacRangeMapping unMappedRange in unMappedRanges)
                {
-                    AlmanacRangeMapping.ClipResult result = rangeMapping.Clip(unMappedRanges[j]);
+                    AlmanacRangeMapping.ClipResult result = rangeMapping.Clip(unMappedRange);
                    if (result.Clipped != null) { mappedRanges.Add(result.Clipped.Value); }
                    if (result.PreClip != null) { newUnMappedRanges.Add(result.PreClip.Value); }
                    if (result.PostClip != null) { newUnMappedRanges.Add(result.PostClip.Value); }
                }
                unMappedRanges = newUnMappedRanges;
-                newUnMappedRanges = new List<AlmanacRangeMapping>();
+                newUnMappedRanges = [];
                i++;
            }

-            return mappedRanges.Union(unMappedRanges).ToList();
+            List<AlmanacRangeMapping> resultMappedRanges = [];
+            resultMappedRanges.AddRange(mappedRanges);
+            resultMappedRanges.AddRange(unMappedRanges);
+            return resultMappedRanges;
        }
    }

@@ -381,7 +377,7 @@ public class Day05 : IDay

        public List<long> Seeds { get; }

-        private List<AlmanacMapping> Mappings { get; } = new();
+        private List<AlmanacMapping> Mappings { get; } = [];

        public static Almanac? Parse(LinesReader reader)
        {
--- a/AdventOfCode2023/Day07.cs
+++ b/AdventOfCode2023/Day07.cs
@@ -114,9 +114,9 @@ public class Day07 : IDay

    public class CamelCard
    {
-        private readonly static char[] Labels = { 'A', 'K', 'Q', 'J', 'T', '9', '8', '7', '6', '5', '4', '3', '2' };
+        private readonly static char[] Labels = ['A', 'K', 'Q', 'J', 'T', '9', '8', '7', '6', '5', '4', '3', '2'];

-        private readonly static char[] LabelsWithJoker = { 'A', 'K', 'Q', 'T', '9', '8', '7', '6', '5', '4', '3', '2', 'J' };
+        private readonly static char[] LabelsWithJoker = ['A', 'K', 'Q', 'T', '9', '8', '7', '6', '5', '4', '3', '2', 'J'];
        private const char JokerLabel = 'J';

        public enum Types
--- a/AdventOfCode2023/Day08.cs
+++ b/AdventOfCode2023/Day08.cs
@@ -105,18 +105,11 @@ public class Day08 : IDay
        return steps.ToString();
    }

-    private class MapNode
+    private class MapNode(string strMapNode)
    {
-        public string Key { get; set; }
-        public string LeftKey { get; set; }
-        public string RightKey { get; set; }
-
-        public MapNode(string strMapNode)
-        {
-            Key = strMapNode.Substring(0, 3);
-            LeftKey = strMapNode.Substring(7, 3);
-            RightKey = strMapNode.Substring(12, 3);
-        }
+        public string Key { get; } = strMapNode.Substring(0, 3);
+        public string LeftKey { get; } = strMapNode.Substring(7, 3);
+        public string RightKey { get; } = strMapNode.Substring(12, 3);
    }

    private class Map
@@ -155,32 +148,23 @@ public class Day08 : IDay
        }
    }

-    private class MapWalker
+    private class MapWalker(Map map, string startKey)
    {
-        private readonly Map _map;
-
-        private MapNode _currentNode;
+        private MapNode _currentNode = map.GetByKey(startKey) ?? map.Nodes.First();
        private long _steps;

-        public MapWalker(Map map, string startKey)
-        {
-            _map = map;
-            _currentNode = map.GetByKey(startKey) ?? map.Nodes.First();
-            _steps = 0;
-        }
-
        public void StepWhile(Func<MapWalker, bool> condition)
        {
            while (condition(this))
            {
-                char leftRightInstruction = _map.GetInstruction(_steps);
+                char leftRightInstruction = map.GetInstruction(_steps);
                if (leftRightInstruction == 'L')
                {
-                    _currentNode = _map.GetByKey(_currentNode.LeftKey) ?? _map.Nodes.First();
+                    _currentNode = map.GetByKey(_currentNode.LeftKey) ?? map.Nodes.First();
                }
                if (leftRightInstruction == 'R')
                {
-                    _currentNode = _map.GetByKey(_currentNode.RightKey) ?? _map.Nodes.First();
+                    _currentNode = map.GetByKey(_currentNode.RightKey) ?? map.Nodes.First();
                }
                _steps++;
            }
--- a/AdventOfCode2023/Day09.cs
+++ b/AdventOfCode2023/Day09.cs
@@ -167,12 +167,12 @@ public class Day09 : IDay

        public long ExtrapolatePast()
        {
-            _derivatives.Last().Insert(0,0);
+            _derivatives.Last().Insert(0, 0);
            for (int i = _derivatives.Count - 2; i >= 0; i--)
            {
                long firstDerivative1 = _derivatives[i].First();
                long firstDerivative0 = _derivatives[i + 1].First();
-                _derivatives[i].Insert(0,firstDerivative1 - firstDerivative0);
+                _derivatives[i].Insert(0, firstDerivative1 - firstDerivative0);
            }
            long firstNumber = _numbers.First();
            long firstDerivative = _derivatives[0].First();
--- a/AdventOfCode2023/Day10.cs
+++ b/AdventOfCode2023/Day10.cs
@@ -228,16 +228,10 @@ public class Day10 : IDay
        return countInside.ToString();
    }

-    private struct Point
+    private struct Point(int x, int y)
    {
-        public int X;
-        public int Y;
-
-        public Point(int x, int y)
-        {
-            X = x;
-            Y = y;
-        }
+        public int X = x;
+        public int Y = y;
    }

    private class PipeMaze
@@ -323,7 +317,7 @@ public class Day10 : IDay
                        x: point.X + 1,
                        y: point.Y);
                }
-                if(point.Y == prevPoint.Y && prevPoint.X > point.X)
+                if (point.Y == prevPoint.Y && prevPoint.X > point.X)
                {
                    return new Point(
                        x: point.X,
@@ -339,7 +333,7 @@ public class Day10 : IDay
                        x: point.X - 1,
                        y: point.Y);
                }
-                if(point.Y == prevPoint.Y && prevPoint.X < point.X)
+                if (point.Y == prevPoint.Y && prevPoint.X < point.X)
                {
                    return new Point(
                        x: point.X,
@@ -355,7 +349,7 @@ public class Day10 : IDay
                        x: point.X - 1,
                        y: point.Y);
                }
-                if(point.Y == prevPoint.Y && prevPoint.X < point.X)
+                if (point.Y == prevPoint.Y && prevPoint.X < point.X)
                {
                    return new Point(
                        x: point.X,
@@ -371,7 +365,7 @@ public class Day10 : IDay
                        x: point.X + 1,
                        y: point.Y);
                }
-                if(point.Y == prevPoint.Y && prevPoint.X > point.X)
+                if (point.Y == prevPoint.Y && prevPoint.X > point.X)
                {
                    return new Point(
                        x: point.X,
@@ -438,10 +432,10 @@ public class Day10 : IDay

        private char CalculateCell(Point point)
        {
-            Point? pointRight =FollowPipe(new Point(point.X + 1, point.Y), point);
-            Point? pointLeft =FollowPipe(new Point(point.X - 1, point.Y), point);
-            Point? pointDown =FollowPipe(new Point(point.X, point.Y + 1), point);
-            Point? pointUp =FollowPipe(new Point(point.X, point.Y - 1), point);
+            Point? pointRight = FollowPipe(new Point(point.X + 1, point.Y), point);
+            Point? pointLeft = FollowPipe(new Point(point.X - 1, point.Y), point);
+            Point? pointDown = FollowPipe(new Point(point.X, point.Y + 1), point);
+            Point? pointUp = FollowPipe(new Point(point.X, point.Y - 1), point);
            if (pointRight != null && pointLeft == null && pointDown != null && pointUp == null)
            {
                return 'F';
@@ -507,12 +501,12 @@ public class Day10 : IDay
                    }
                    else if (cell == 'J')
                    {
-                        if(cellStart == 'F')
+                        if (cellStart == 'F')
                        {
                            inside = inside != true;
                            cellStart = null;
                        }
-                        else if(cellStart == 'L')
+                        else if (cellStart == 'L')
                        {
                            cellStart = null;
                        }
@@ -523,23 +517,23 @@ public class Day10 : IDay
                        {
                            cellStart = 'F';
                        }
-                        else if(cellStart == 'J')
+                        else if (cellStart == 'J')
                        {
                            inside = inside != true;
                            cellStart = null;
                        }
-                        else if(cellStart == '7')
+                        else if (cellStart == '7')
                        {
                            cellStart = null;
                        }
                    }
                    else if (cell == '7')
                    {
-                        if(cellStart == 'F')
+                        if (cellStart == 'F')
                        {
                            cellStart = null;
                        }
-                        else if(cellStart == 'L')
+                        else if (cellStart == 'L')
                        {
                            inside = inside != true;
                            cellStart = null;
@@ -551,11 +545,11 @@ public class Day10 : IDay
                        {
                            cellStart = 'L';
                        }
-                        else if(cellStart == 'J')
+                        else if (cellStart == 'J')
                        {
                            cellStart = null;
                        }
-                        else if(cellStart == '7')
+                        else if (cellStart == '7')
                        {
                            inside = inside != true;
                            cellStart = null;
--- a/AdventOfCode2023/Day11.cs
+++ b/AdventOfCode2023/Day11.cs
@@ -130,8 +130,8 @@ public class Day11 : IDay

    private struct Point
    {
-        public long X { get; set; }
-        public long Y { get; set; }
+        public long X { get; init; }
+        public long Y { get; init; }
    }

    private class GalaxyMap
--- a/AdventOfCode2023/Day12.cs
+++ b/AdventOfCode2023/Day12.cs
@@ -1,4 +1,3 @@
-using System.Text;

 namespace AdventOfCode2023;

--- a/AdventOfCode2023/Day24.cs
+++ b/AdventOfCode2023/Day24.cs
@@ -103,24 +103,17 @@ public class Day24 : IDay
        throw new NotImplementedException();
    }

-    public struct Vector3D
+    public struct Vector3D(long x, long y, long z)
    {
-        public readonly long X;
-        public readonly long Y;
-        public readonly long Z;
-
-        public Vector3D(long x, long y, long z)
-        {
-            X = x;
-            Y = y;
-            Z = z;
-        }
+        public readonly long X = x;
+        public readonly long Y = y;
+        public readonly long Z = z;
    }

    public readonly struct Hail
    {
        public readonly Vector3D Position;
-        public readonly Vector3D Velocity;
+        private readonly Vector3D _velocity;

        public Hail(string input)
        {
@@ -131,7 +124,7 @@ public class Day24 : IDay
                y: Convert.ToInt64(strPosition[1]),
                z: Convert.ToInt64(strPosition[2]));
            string[] strVelocity = parts[1].Split(", ");
-            Velocity = new Vector3D(
+            _velocity = new Vector3D(
                x: Convert.ToInt64(strVelocity[0]),
                y: Convert.ToInt64(strVelocity[1]),
                z: Convert.ToInt64(strVelocity[2]));
@@ -139,21 +132,21 @@ public class Day24 : IDay

        public (bool intersects, double s, double t, Vector3D point) Intersect2D(Hail other)
        {
-            long s_Div = (-other.Velocity.X * Velocity.Y + Velocity.X * other.Velocity.Y);
+            long s_Div = (-other._velocity.X * _velocity.Y + _velocity.X * other._velocity.Y);
            if (s_Div == 0)
            {
                return (false, 0, 0, new Vector3D());
            }
-            double s = (-Velocity.Y * (Position.X - other.Position.X) + Velocity.X * (Position.Y - other.Position.Y)) / (double)s_Div;
+            double s = (-_velocity.Y * (Position.X - other.Position.X) + _velocity.X * (Position.Y - other.Position.Y)) / (double)s_Div;

-            long t_Div = (-other.Velocity.X * Velocity.Y + Velocity.X * other.Velocity.Y);
+            long t_Div = (-other._velocity.X * _velocity.Y + _velocity.X * other._velocity.Y);
            if (t_Div == 0)
            {
                return (false, 0, 0, new Vector3D());
            }
-            double t = (other.Velocity.X * (Position.Y - other.Position.Y) - other.Velocity.Y * (Position.X - other.Position.X)) / (double)t_Div;
+            double t = (other._velocity.X * (Position.Y - other.Position.Y) - other._velocity.Y * (Position.X - other.Position.X)) / (double)t_Div;

-            Vector3D intersection = new((long)(Position.X + t * Velocity.X), (long)(Position.Y + t * Velocity.Y), 0);
+            Vector3D intersection = new((long)(Position.X + t * _velocity.X), (long)(Position.Y + t * _velocity.Y), 0);
            return (true, s, t, intersection);
        }
    }
--- a/AdventOfCode2024.Tests/AdventOfCode2024.Tests.csproj
+++ b/AdventOfCode2024.Tests/AdventOfCode2024.Tests.csproj
@@ -0,0 +1,26 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net8.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+        <RootNamespace>AdventOfCode2024.Tests</RootNamespace>
+
+        <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.6.0"/>
+        <PackageReference Include="xunit" Version="2.4.2"/>
+        <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">
+            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+            <PrivateAssets>all</PrivateAssets>
+        </PackageReference>
+    </ItemGroup>
+
+    <ItemGroup>
+        <ProjectReference Include="..\AdventOfCode2024\AdventOfCode2024.csproj"/>
+    </ItemGroup>
+
+</Project>
--- a/AdventOfCode2024.Tests/Day01_Tests.cs
+++ b/AdventOfCode2024.Tests/Day01_Tests.cs
@@ -0,0 +1,38 @@
+namespace AdventOfCode2024.Tests;
+
+public class Day01_Tests
+{
+    [Fact]
+    public void ResolvePart1__Example()
+    {
+        Day01 day = new();
+
+        string result = day.ResolvePart1([
+            "3   4",
+            "4   3",
+            "2   5",
+            "1   3",
+            "3   9",
+            "3   3",
+        ]);
+
+        Assert.Equal("11", result);
+    }
+
+    [Fact]
+    public void ResolvePart2__Example()
+    {
+        Day01 day = new();
+
+        string result = day.ResolvePart2([
+            "3   4",
+            "4   3",
+            "2   5",
+            "1   3",
+            "3   9",
+            "3   3",
+        ]);
+
+        Assert.Equal("31", result);
+    }
+}
--- a/AdventOfCode2024.Tests/Day02_Tests.cs
+++ b/AdventOfCode2024.Tests/Day02_Tests.cs
@@ -0,0 +1,38 @@
+namespace AdventOfCode2024.Tests;
+
+public class Day02_Tests
+{
+    [Fact]
+    public void ResolvePart1__Example()
+    {
+        Day02 day = new();
+
+        string result = day.ResolvePart1([
+            "7 6 4 2 1",
+            "1 2 7 8 9",
+            "9 7 6 2 1",
+            "1 3 2 4 5",
+            "8 6 4 4 1",
+            "1 3 6 7 9",
+        ]);
+
+        Assert.Equal("2", result);
+    }
+    
+    [Fact]
+    public void ResolvePart2__Example()
+    {
+        Day02 day = new();
+
+        string result = day.ResolvePart2([
+            "7 6 4 2 1",
+            "1 2 7 8 9",
+            "9 7 6 2 1",
+            "1 3 2 4 5",
+            "8 6 4 4 1",
+            "1 3 6 7 9",
+        ]);
+
+        Assert.Equal("4", result);
+    }
+}
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Valeriano A.R.	31e0259e24	Sync	2025-08-01 06:15:44 +02:00
Valeriano A.R.	b68ee2259a	AdventOfCode2024 Day04	2024-12-05 01:23:46 +01:00
Valeriano A.R.	7a06bc7172	AdventOfCode2024 Day03 Part 2	2024-12-03 12:04:17 +01:00
Valeriano A.R.	2662c17c60	AdventOfCode2024 Day03 Part 1	2024-12-03 11:53:06 +01:00
Valeriano A.R.	a5173f623d	AdventOfCode2024 Day02	2024-12-02 08:21:07 +01:00
Valeriano A.R.	f8342dea26	Use target-type new.	2024-12-02 07:55:58 +01:00
Valeriano A.R.	e440e7aae1	Apply nullability	2024-12-02 01:37:52 +01:00
Valeriano A.R.	dafd2526d1	Code formatting and warning fixing.	2024-12-01 17:36:23 +01:00
Valeriano A.R.	9f8d966b7a	AdventOfCode2024 Day01 Part 2	2024-12-01 07:55:28 +01:00
Valeriano A.R.	39b543346d	AdventOfCode2024 Day01 Part 1	2024-12-01 07:49:47 +01:00
Valeriano A.R.	c30fc4bf51	Migrate to SLNX solution file format.	2024-12-01 07:40:14 +01:00
Valeriano A.R.	c2d956ac88	Add AdventOfCode2024 projects	2024-12-01 07:36:28 +01:00
Valeriano A.R.	0571e443b8	WIP	2024-05-20 20:03:04 +02:00
Valeriano A.R.	1efbc4acd6	Update to dotnet 8	2024-04-16 23:07:37 +02:00