Day08 part 2

AdventOfCode2018.Tests/Day08_Tests.cs

@@ -14,5 +14,15 @@ namespace AdventOfCode2018.Tests
 
             Assert.AreEqual("138", result);
         }
+
+        [TestMethod()]
+        public void ResolvePart2__Test()
+        {
+            Day08 day = new Day08();
+
+            string result = day.ResolvePart2(new string[] { "2 3 0 3 10 11 12 1 1 0 1 99 2 1 1 2", });
+
+            Assert.AreEqual("66", result);
+        }
     }
 }

AdventOfCode2018/Day08.cs

@@ -41,6 +41,25 @@ namespace AdventOfCode2018
 
     What is the sum of all metadata entries?
 
+    --- Part Two ---
+
+    The second check is slightly more complicated: you need to find the value of the root node (A in the example above).
+
+    The value of a node depends on whether it has child nodes.
+
+    If a node has no child nodes, its value is the sum of its metadata entries. So, the value of node B is 10+11+12=33, and the value of node D is 99.
+
+    However, if a node does have child nodes, the metadata entries become indexes which refer to those child nodes. A metadata entry of 1 refers to the first child node, 2 to the second, 3 to the third, and so on. The value of this node is the sum of the values of the child nodes referenced by the metadata entries. If a referenced child node does not exist, that reference is skipped. A child node can be referenced multiple time and counts each time it is referenced. A metadata entry of 0 does not refer to any child node.
+
+    For example, again using the above nodes:
+
+        Node C has one metadata entry, 2. Because node C has only one child node, 2 references a child node which does not exist, and so the value of node C is 0.
+        Node A has three metadata entries: 1, 1, and 2. The 1 references node A's first child node, B, and the 2 references node A's second child node, C. Because node B has a value of 33 and node C has a value of 0, the value of node A is 33+33+0=66.
+
+    So, in this example, the value of the root node is 66.
+
+    What is the value of the root node?
+
     */
 
     public class Day08 : IDay
@@ -55,9 +74,13 @@ namespace AdventOfCode2018
 
         public string ResolvePart2(string[] inputs)
         {
-            return null;
+            IntStream values = new IntStream(inputs[0]);
+            ChronoLicenceNode licenceTree = ChronoLicenceNode.BuildFromIntStream(values);
+            int result = licenceTree.GetValue();
+            return result.ToString();
         }
     }
+
     public class IntStream
     {
         private int[] values;
@@ -66,7 +89,7 @@ namespace AdventOfCode2018
         public IntStream(string strValues)
         {
             values = strValues
-                .Split(new string[] { " ", "" }, StringSplitOptions.RemoveEmptyEntries)
+                .Split(new string[] { " ", }, StringSplitOptions.RemoveEmptyEntries)
                 .Select(strVal => Convert.ToInt32(strVal))
                 .ToArray();
             index = 0;
@@ -115,5 +138,24 @@ namespace AdventOfCode2018
             }
             return checksum;
         }
+
+        public int GetValue()
+        {
+            int value = 0;
+            if (Childs.Count == 0)
+            {
+                value = Metadata.Sum();
+            }
+            else
+            {
+                foreach (int metadata in Metadata)
+                {
+                    int index = metadata - 1;
+                    if (index < 0 || index >= Childs.Count) { continue; }
+                    value += Childs[index].GetValue();
+                }
+            }
+            return value;
+        }
     }
 }