Day 8 part 2

AoC2018.Solutions/Day08/NodeExtensions.cs

@@ -0,0 +1,29 @@
+namespace AoC2018.Solutions.Day08
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+
+    public static class NodeExtensions
+    {
+        public static int MetadataChecksum(this Node[] nodes)
+        {
+            return nodes.Sum(x => x.MetadataChecksum());
+        }
+
+        public static int MetadataChecksum(this Node node)
+        {
+            return node.Metadata.Sum() + node.Children.MetadataChecksum();
+        }
+
+        public static int Value(this Node node)
+        {
+            if (node.Children.Length == 0)
+            {
+                return node.Metadata.Sum();
+            }
+
+            return node.Metadata.Sum(x => (x > 0 && x <= node.Children.Length) ? node.Children[x - 1].Value() : 0);
+        }
+    }
+}

AoC2018.Solutions/Day08/Part01.cs

@@ -10,7 +10,7 @@ public string Solve(string input)
         {
             var licenceFile = LicenceFile.Parse(input);
 
-            return licenceFile.MetadataChecksum().ToString();
+            return licenceFile.RootNodes.MetadataChecksum().ToString();
         }
     }
 }

AoC2018.Solutions/Day08/Part02.cs

@@ -0,0 +1,16 @@
+namespace AoC2018.Solutions.Day08
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+
+    public class Part02 : ISolution
+    {
+        public string Solve(string input)
+        {
+            var licenceFile = LicenceFile.Parse(input);
+
+            return licenceFile.RootNodes[0].Value().ToString();
+        }
+    }
+}

AoC2018.Tests/AoCTestCases.cs

@@ -32,6 +32,7 @@ public class AoCTestCases
         [TestCase(6, 1, "1, 1\r\n1, 6\r\n8, 3\r\n3, 4\r\n5, 5\r\n8, 9", "17")]
         [TestCase(7, 1, "Step C must be finished before step A can begin.\r\nStep C must be finished before step F can begin.\r\nStep A must be finished before step B can begin.\r\nStep A must be finished before step D can begin.\r\nStep B must be finished before step E can begin.\r\nStep D must be finished before step E can begin.\r\nStep F must be finished before step E can begin.", "CABDFE")]
         [TestCase(8, 1, "2 3 0 3 10 11 12 1 1 0 1 99 2 1 1 2", "138")]
+        [TestCase(8, 2, "2 3 0 3 10 11 12 1 1 0 1 99 2 1 1 2", "66")]
         public void Tests(int day, int part, string input, string expectedResult)
         {
             ISolution solution = SolutionFactory.GetSolution(day, part);