AdventOfCode 2023 Day08 Part1

AdventOfCode2023/Day08.cs

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+namespace AdventOfCode2023;
+
+/*
+--- Day 8: Haunted Wasteland ---
+
+You're still riding a camel across Desert Island when you spot a sandstorm quickly approaching. When you turn to warn the Elf, she disappears before your eyes! To be fair, she had just finished warning you about ghosts a few minutes ago.
+
+One of the camel's pouches is labeled "maps" - sure enough, it's full of documents (your puzzle input) about how to navigate the desert. At least, you're pretty sure that's what they are; one of the documents contains a list of left/right instructions, and the rest of the documents seem to describe some kind of network of labeled nodes.
+
+It seems like you're meant to use the left/right instructions to navigate the network. Perhaps if you have the camel follow the same instructions, you can escape the haunted wasteland!
+
+After examining the maps for a bit, two nodes stick out: AAA and ZZZ. You feel like AAA is where you are now, and you have to follow the left/right instructions until you reach ZZZ.
+
+This format defines each node of the network individually. For example:
+
+RL
+
+AAA = (BBB, CCC)
+BBB = (DDD, EEE)
+CCC = (ZZZ, GGG)
+DDD = (DDD, DDD)
+EEE = (EEE, EEE)
+GGG = (GGG, GGG)
+ZZZ = (ZZZ, ZZZ)
+
+Starting with AAA, you need to look up the next element based on the next left/right instruction in your input. In this example, start with AAA and go right (R) by choosing the right element of AAA, CCC. Then, L means to choose the left element of CCC, ZZZ. By following the left/right instructions, you reach ZZZ in 2 steps.
+
+Of course, you might not find ZZZ right away. If you run out of left/right instructions, repeat the whole sequence of instructions as necessary: RL really means RLRLRLRLRLRLRLRL... and so on. For example, here is a situation that takes 6 steps to reach ZZZ:
+
+LLR
+
+AAA = (BBB, BBB)
+BBB = (AAA, ZZZ)
+ZZZ = (ZZZ, ZZZ)
+
+Starting at AAA, follow the left/right instructions. How many steps are required to reach ZZZ?
+
+
+*/
+
+public class Day08 : IDay
+{
+    public string ResolvePart1(string[] inputs)
+    {
+        string startNodeKey = "AAA";
+        string endNodeKey = "ZZZ";
+        string strLeftRightInstructions = inputs[0];
+        Dictionary<string, MapNode> dictNodes = new();
+        for (int i = 2; i < inputs.Length; i++)
+        {
+            MapNode node = new(inputs[i]);
+            dictNodes.Add(node.Key, node);
+        }
+
+        MapNode currentNode = dictNodes[startNodeKey];
+        int steps = 0;
+        while (currentNode.Key != endNodeKey)
+        {
+            char leftRightInstruction = strLeftRightInstructions[steps % strLeftRightInstructions.Length];
+            if (leftRightInstruction == 'L')
+            {
+                currentNode = dictNodes[currentNode.LeftKey];
+            }
+            if (leftRightInstruction == 'R')
+            {
+                currentNode = dictNodes[currentNode.RightKey];
+            }
+            steps++;
+        }
+        return steps.ToString();
+    }
+
+    public string ResolvePart2(string[] inputs)
+    {
+        throw new NotImplementedException();
+    }
+
+    public class MapNode
+    {
+        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);
+        }
+    }
+}