Day 24

I solved this by hand, so there's no code solving it programmatically. Maybe I'll come back later and solve it with code...

advent-of-code-2021.csproj

@@ -87,6 +87,9 @@
 	  <None Update="inputs\23.txt">
 	    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
 	  </None>
+	  <None Update="inputs\24.txt">
+	    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+	  </None>
 	</ItemGroup>
 
 </Project>

inputs/24.txt

@@ -0,0 +1,255 @@
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 11
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 6
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 13
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 14
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 15
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 14
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -8
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 10
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 13
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 9
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 15
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 12
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -11
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 8
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -4
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 13
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -15
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 12
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 14
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 6
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 1
+add x 14
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 9
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -1
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 15
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -8
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 4
+mul y x
+add z y
+inp w
+mul x 0
+add x z
+mod x 26
+div z 26
+add x -14
+eql x w
+eql x 0
+mul y 0
+add y 25
+mul y x
+add y 1
+mul z y
+mul y 0
+add y w
+add y 10
+mul y x
+add z y
+
+     101011000001011100001001101
+10001011110100101011011101110101

src/24.cs

@@ -0,0 +1,176 @@
+using System.Diagnostics;
+
+namespace aoc2021;
+
+internal class Day24 : Day
+{
+    public record struct Instruction(string Opcode, char Op1, string? Op2);
+
+    [DebuggerDisplay("Input: {InputStr}, w: {w}, x: {x}, y: {y}, z: {z}")]
+    public class Machine
+    {
+        public string InputStr;
+        private int InputStrIdx = 0;
+        public long w = 0;
+        public long x = 0;
+        public long y = 0;
+        public long z = 0;
+
+        public Machine(string input)
+        {
+            InputStr = input;
+        }
+
+        public void ProcessInstruction(Instruction inst)
+        {
+            switch (inst.Opcode)
+            {
+                case "inp":
+                    StoreValue(inst.Op1, (long)char.GetNumericValue(InputStr[InputStrIdx]));
+                    InputStrIdx++;
+                    break;
+
+                default:
+                    var val = RetrieveValue(inst.Op1);
+                    switch (inst.Opcode)
+                    {
+                        case "add":
+                            val += GetValue(inst.Op2!);
+                            break;
+
+                        case "mul":
+                            val *= GetValue(inst.Op2!);
+                            break;
+
+                        case "div":
+                            val /= GetValue(inst.Op2!);
+                            break;
+
+                        case "mod":
+                            val %= GetValue(inst.Op2!);
+                            break;
+
+                        case "eql":
+                            var b = GetValue(inst.Op2!);
+                            val = val == b ? 1 : 0;
+                            break;
+
+                        default:
+                            throw new Exception();
+                    }
+                    StoreValue(inst.Op1, val);
+                    break;
+            }
+        }
+
+        public long GetValue(string op2)
+        {
+            if (long.TryParse(op2, out long iop2))
+            {
+                return iop2;
+            }
+
+            return RetrieveValue(op2[0]);
+        }
+
+        public long RetrieveValue(char var) => var switch
+        {
+            'w' => w,
+            'x' => x,
+            'y' => y,
+            'z' => z,
+            _ => throw new Exception(),
+        };
+
+        public void StoreValue(char var, long value)
+        {
+            switch (var)
+            {
+                case 'w':
+                    w = value;
+                    break;
+
+                case 'x':
+                    x = value;
+                    break;
+
+                case 'y':
+                    y = value;
+                    break;
+
+                case 'z':
+                    z = value;
+                    break;
+
+                default:
+                    throw new Exception();
+            }
+        }
+    }
+
+    internal override void Go()
+    {
+        var lines = Util.ReadAllLines("inputs/24.txt");
+        List<Instruction> instructions = new();
+        foreach (var line in lines)
+        {
+            if (string.IsNullOrEmpty(line))
+            {
+                break;
+            }
+
+            var inst = line.Split(' ', 2);
+            switch (inst[0])
+            {
+                case "inp":
+                    instructions.Add(new Instruction(inst[0], inst[1][0], null));
+                    break;
+
+                default:
+                    {
+                        var operands = inst[1].Split(' ');
+                        instructions.Add(new Instruction(inst[0], operands[0][0], operands[1]));
+                    }
+                    break;
+            }
+        }
+        Part1(instructions);
+        Part2(instructions);
+    }
+
+    private static void Part1(IList<Instruction> instructions)
+    {
+        using var t = new Timer();
+
+        Machine m = new("99394899891971");
+        foreach (var inst in instructions)
+        {
+            m.ProcessInstruction(inst);
+        }
+        if (m.z != 0)
+        {
+            throw new Exception();
+        }
+
+        t.Stop();
+        Logger.Log($"<+black>> part1: <+white>99394899891971<r>");
+    }
+
+    private static void Part2(IList<Instruction> instructions)
+    {
+        using var t = new Timer();
+
+        Machine m = new("92171126131911");
+        foreach (var inst in instructions)
+        {
+            m.ProcessInstruction(inst);
+        }
+        if (m.z != 0)
+        {
+            throw new Exception();
+        }
+
+        t.Stop();
+        Logger.Log($"<+black>> part2: <+white>92171126131911<r>");
+    }
+}

src/main.cs

@@ -20,7 +20,7 @@ else
     Day? day = null;
     if (string.IsNullOrEmpty(arg))
     {
-        day = new Day23();
+        day = new Day24();
     }
     else
     {