From a0d8bc1f07970a4f7c2113621bbc904170f71dc8 Mon Sep 17 00:00:00 2001
From: Ben Harris <ben@tilde.team>
Date: Tue, 14 Nov 2023 15:40:45 -0500
Subject: [PATCH] 2015 day 23

---
 AOC.Test/Test2015.cs |  1 +
 AOC2015/Day23.cs     | 45 +++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/AOC.Test/Test2015.cs b/AOC.Test/Test2015.cs
index 0d73fa4..640e519 100644
--- a/AOC.Test/Test2015.cs
+++ b/AOC.Test/Test2015.cs
@@ -27,6 +27,7 @@ public class Test2015
     [DataRow(typeof(Day19), "576", "207")]
     [DataRow(typeof(Day20), "665280", "705600")]
     [DataRow(typeof(Day21), "78", "148")]
+    [DataRow(typeof(Day23), "255", "334")]
     public void CheckAllDays(Type dayType, string part1, string part2)
     {
         Common.CheckDay(dayType, part1, part2);
diff --git a/AOC2015/Day23.cs b/AOC2015/Day23.cs
index c0ce8cb..afa19a9 100644
--- a/AOC2015/Day23.cs
+++ b/AOC2015/Day23.cs
@@ -9,7 +9,46 @@ public sealed class Day23() : Day(2015, 23, "Opening the Turing Lock")
     {
     }
 
-    public override object Part1() => "";
+    private int RunOperations(int initialA = 0, int initialB = 0)
+    {
+        Dictionary<char, int> registers = new();
+        registers['a'] = initialA;
+        registers['b'] = initialB;
 
-    public override object Part2() => "";
-}
+        var input = Input.ToList();
+        for (var i = 0; i < input.Count;)
+        {
+            switch (input[i][0..3])
+            {
+                case "hlf":
+                    registers[input[i++][4]] /= 2;
+                    break;
+                case "tpl":
+                    registers[input[i++][4]] *= 3;
+                    break;
+                case "inc":
+                    registers[input[i++][4]]++;
+                    break;
+                case "jmp":
+                    i += int.Parse(input[i][4..]);
+                    break;
+                case "jie":
+                    i += registers[input[i][4]] % 2 == 0
+                        ? int.Parse(input[i][7..])
+                        : 1;
+                    break;
+                case "jio":
+                    i += registers[input[i][4]] == 1
+                        ? int.Parse(input[i][7..])
+                        : 1;
+                    break;
+            }
+        }
+
+        return registers['b'];
+    }
+
+    public override object Part1() => RunOperations();
+
+    public override object Part2() => RunOperations(1);
+}
\ No newline at end of file