AdventOfCode/AoC_2025/Day10.cs

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.Common;
using System.IO;
using System.Linq;
using AdvenOfCode.Contracts;
using Microsoft.Z3;

namespace AoC_2025;

public class Day10 : IPuzzleSolver<long>
{
    private (uint lamps, (int[] buttons, uint buttonsMap)[] buttons, int[] joltages)[] ParsePuzzleInput(string path)
    {
        var puzzleInput = File.ReadAllLines(path)
            .Where(line => !string.IsNullOrWhiteSpace(line))
            .Select(line => line.Split(' ', StringSplitOptions.RemoveEmptyEntries))
            .Select(instruction => instruction switch
            {
                [var lamps, ..var buttons, var joltages] => (lamps: lamps[1..^1], buttons, joltages: joltages[1..^1]),
                _ => throw new DataException("Misaligned data")
            })
            .OrderBy(inst => inst.lamps.Length)
            .ToArray();
        var lamps = puzzleInput
            .Select(input => input.lamps)
            .Select(lamps => lamps.Index())
            .Select(ixlamps =>
                ixlamps.Aggregate((uint)0L, (acc, ixLamp) => acc | ((uint)(ixLamp.Item == '#' ? 1L : 0L) << ixLamp.Index)))
            .ToArray();
        var buttons = puzzleInput
            .Select(input => input.buttons)
            .Select(buttons => buttons
                .Select(button => button[1..^1]
                    .Split(',', StringSplitOptions.RemoveEmptyEntries)
                    .Select(lampIndex => int.Parse(lampIndex))
                    .ToArray())
                .Select(lampIndexes => (lampIndexes, lampIndexes.Aggregate((uint)0L, (acc, lampIndex) => acc | ((uint)1 << lampIndex))))
                .ToArray())
            .ToArray();
        var joltages = puzzleInput
            .Select(input => input.joltages)
            .Select(joltage => joltage
                .Split(',', StringSplitOptions.RemoveEmptyEntries)
                .Select(jolt => int.Parse(jolt))
                .ToArray())
            .ToArray();
        var res = lamps
            .Zip(buttons, (lamp, button) => (lamp, button))
            .Zip(joltages, (bl, joltage) => (bl.lamp, bl.button, joltage))
            .ToArray();
        return res;
    }

    public long SolvePart1(string pathToPuzzleInput)
    {
        var instructions = ParsePuzzleInput(pathToPuzzleInput);
        var minCounts = instructions
            .Select(ins => GetMinCountButtonPressesForLamps(ins.lamps, [..ins.buttons.Select(b => b.buttonsMap)]))
            .ToArray();
        return minCounts.Sum();
    }

    public long SolvePart2(string pathToPuzzleInput)
    {
        var instructions = ParsePuzzleInput(pathToPuzzleInput);
        var minCounts = instructions
            .Select(ins => GetMinCountButtonPressesForJoltages(ins.joltages, [..ins.buttons.Select(b => b.buttons)]))
            .ToArray();
        var sum = minCounts.Sum();
        return sum;
    }

    private long GetMinCountButtonPressesForLamps(uint lamps, uint[] buttons)
    {
        var presses = 0L;
        HashSet<uint> lampStates = [lamps];
        while (lampStates.All(state => state > 0) && presses < 100)
        {
            lampStates = lampStates
                .Select(lampState => GetLampStates(lampState, buttons))
                .Aggregate((current, states) => [..current,..states])
                .ToHashSet();
            presses++;
        }
        
        return presses;
    }

    private uint[] GetLampStates(uint lampState, uint[] buttons)
    {
        var states = buttons
            .Where(button => (lampState & button) > 0)
            .Select(button => lampState ^ button);
        return [..states];
    }

    private long GetMinCountButtonPressesForJoltages(int[] joltages, int[][] buttons)
    {
        using var context = new Context();
        var optimize = context.MkOptimize();
        var variables = Enumerable.Range(0, buttons.Length)
            .Select(ix => context.MkIntConst($"n{ix}"))
            .ToArray();
        foreach (var variable in variables)
        {
            optimize.Add(variable >= 0);
        }

        var zero = context.MkInt(0);
        foreach (var (i, joltage) in joltages.Index())
        {
            var equation = zero + zero;
            
            foreach (var (b, button) in buttons.Index())
            {
                if(button.Contains(i))
                    equation += variables[b];
            }

            optimize.Add(context.MkEq(equation, context.MkInt(joltage)));
        }
        var sumVariables = variables.Aggregate(zero + zero, (current, variable) => current + variable);

        optimize.MkMinimize(sumVariables);
        optimize.Check();
        var answerExpression = optimize.Model.Eval(sumVariables);
        var answer = answerExpression is IntNum number ? number.Int64 : 0;
        return answer;
    }
}