2021aoc/Day24.cs

// #define Day24
#if Day24
using System.Diagnostics;
using AoC2021;

var varPos = "wxyz";


var allOperations = File.ReadAllLines("day24/input")
    .Select(l => l.Split(" "))
    .Select(parts =>
        parts.Length == 2
            ? new Operation(Enum.Parse<Op>(parts[0]), varPos.IndexOf(parts[1][0]), "do not use")
            : new Operation(Enum.Parse<Op>(parts[0]), varPos.IndexOf(parts[1][0]), parts[2])
    )
    .ToList();

var operationSections = new List<List<Operation>>();
var curOperations = new List<Operation>();
foreach (var op in allOperations) {
    if (op.op != Op.inp) {
        curOperations.Add(op);
        continue;
    }

    if (curOperations.Count == 0) {
        curOperations.Add(op);
        continue;
    }

    operationSections.Add(curOperations);
    curOperations = new List<Operation>() { op };
}

operationSections.Add(curOperations);
operationSections.Reverse();

var starting = new ZW(0, "0");
var prev = new HashSet<ZW>() {starting};

var sw = new Stopwatch();
sw.Start();
int countSections = 0;
long maxZ = 0;
foreach (var section in operationSections) {
    sw.Stop();
    Console.WriteLine(sw.Elapsed);
    Console.WriteLine($"prev count: {prev.Count}");
    sw.Restart();
    Console.WriteLine($"countSections: {countSections++}");
    var validZWMax = prev.GroupBy(x => x.z).ToDictionary(g => g.Key, g => g.MaxBy(x => long.Parse(x.w)));
    var validZWMin = prev.GroupBy(x => x.z).ToDictionary(g => g.Key, g => g.MinBy(x => long.Parse(x.w)));
    maxZ = Math.Max(maxZ, validZWMax.Keys.Max());
    Console.WriteLine($"maxZ: {maxZ}");
    Console.WriteLine($"cur maxZ: {validZWMax.Keys.Max()}");
    var next = new HashSet<ZW>();
    if (section.Equals(operationSections.Last())) {
        // z has to be 0 in the last part
        for (int w = 1; w <= 9; w++) {
            var resultZ = CheckMonad(w.ToString(), 0, section);
            if (validZWMax.Keys.Contains(resultZ)) {
                next.Add(new ZW(0, w + validZWMax[resultZ].w));
                next.Add(new ZW(0, w + validZWMin[resultZ].w));
            }
        }
        prev = next;
        continue;
    }

    for (int initialZ = 0; initialZ < 10000000; initialZ++) {
        for (int w = 1; w <= 9; w++) {
            var resultZ = CheckMonad(w.ToString(), initialZ, section);
            if (validZWMax.Keys.Contains(resultZ)) {
                next.Add(new ZW(initialZ, w + validZWMax[resultZ].w));
                next.Add(new ZW(initialZ, w + validZWMin[resultZ].w));
            }
        }
    }
    prev = next;
    if (prev.Count == 0) {
        Console.WriteLine("something went wrong!");
    }
}

sw.Stop();
Console.WriteLine(sw.Elapsed);
Console.WriteLine($"maxZ: {maxZ}");
Console.WriteLine($"prev count: {prev.Count}");
prev.ToList().ForEach(Console.WriteLine);

// for (int z = 0; z < 100000; z++) {
//     for (int j = 1; j <= 9; j++) {
//             var result = CheckMonad(j.ToString(), z, allOperations);
//             if (result >= 0 && result <= 6) {
//                 Console.WriteLine($"z: {z}, w: {j}, res: {result}");
//             }
//     }
// }

// for (int z = 0; z < 100000; z++) {
    // for (int j = 1; j <= 9; j++) {
    //     for (int k = 1; k <= 9; k++) {
    //         var result = CheckMonad(j.ToString() + k.ToString(), 0, allOperations);
    //         if (result >= 0 && result <= 6) {
    //             Console.WriteLine($"z: 0, w: {j}{k}, res: {result}");
    //         }
    //     }
    // }
// }

// var result = CheckMonad("2");
// Console.WriteLine(result);

// Console.WriteLine(CheckMonad("13579246899999"));
// long count = 0;
// for (long i = 99999999999999; i >= 11111111111111; i--) {
//     string iToCheck = i.ToString();
//     if (iToCheck.Contains('0')) {
//         continue;
//     }
//     if (count % 100 == 0) {
//         Console.WriteLine(count);
//     }
//     if (CheckMonad(iToCheck)) {
//         Console.WriteLine(iToCheck);
//
//         break;
//     }
//     count++;
// }



long CheckMonad(string toCheck, int initialZ, List<Operation> operations) {
    int monadPos = 0;
    var variables =  new List<long>() {0,0,0,initialZ};// Enumerable.Repeat(0L, 4).ToList();
    foreach (var op in operations) {
        // varPos.ForEachIndex((c, i) => Console.Write($"{c}: {variables[i]}, "));
        // Console.WriteLine();
        if (op.op == Op.inp) {
            ReadInput(op, toCheck, variables, ref monadPos);
        } else {
            Calc(op, variables);
        }
    }

    // varPos.ForEachIndex((c, i) => Console.Write($"{c}: {variables[i]}, "));
    // Console.WriteLine();

    // return variables[varPos.IndexOf('z')] == 0;
    return variables[varPos.IndexOf('z')];
}


void ReadInput(Operation op, string toCheck, List<long> variables, ref int monadPos) {
    variables[op.aPos] = long.Parse(toCheck[monadPos].ToString());
    monadPos++;
}

void Calc(Operation op, List<long> variables) {
    long b;
    if (op.b.Length == 1 && varPos.Contains(op.b[0])) {
        b = variables[varPos.IndexOf(op.b[0])];
    } else {
        b = long.Parse(op.b);
    }

    variables[op.aPos] = op.op switch {
        Op.add => variables[op.aPos] + b,
        Op.mul => variables[op.aPos] * b,
        Op.div => variables[op.aPos] / b,
        Op.mod => variables[op.aPos] % b,
        Op.eql => variables[op.aPos] == b ? 1 : 0,
        _ => throw new ArgumentException()
    };
}

enum Op{
    inp, add, mul, div, mod, eql
}

record Operation(Op op, int aPos, string b);

record ZW(long z, string w);
#endif