AdventOfCode/2024/Day03CSharp/Program.cs

using System.Numerics;
using System.Text.RegularExpressions;

var exParsed = new Day03Parsed("example-input.txt");
var ex2Parsed = new Day03Parsed("example-input2.txt");

Console.WriteLine("Example Part01: {0}", exParsed.GetPart01());
Console.WriteLine("Example Part02: {0}", ex2Parsed.GetPart02());

var pzParsed = new Day03Parsed("puzzle-input.txt");

Console.WriteLine("Puzzle Part01: {0}", pzParsed.GetPart01());
Console.WriteLine("Puzzle Part02: {0}", pzParsed.GetPart02());


public class Mul
{
    private static readonly int INVALID_VALUE = 9999;

    private int leftOperand = INVALID_VALUE;
    private int rightOperand = INVALID_VALUE;

    public int LeftOperand { get { return leftOperand; } }
    public int RightOperand { get { return rightOperand; } }

    public Mul(string line)
    {
        try
        {
            var split = line.Split(',');

            // left side
            var leftOperand = split[0].Substring("mul(".Length);
            System.Diagnostics.Debug.Assert(leftOperand.Length <= 3);

            this.leftOperand = Int32.Parse(leftOperand);

            // right side
            var rightOperand = split[1].Split(')')[0];
            System.Diagnostics.Debug.Assert(rightOperand.Length <= 3);

            this.rightOperand = Int32.Parse(rightOperand);
        } 
        catch (Exception)
        {

        }
    }

    public bool IsValid()
    {
        return leftOperand != INVALID_VALUE && rightOperand != INVALID_VALUE;
    }

    public int GetResult()
    {
        if (!IsValid()) throw new Exception("OBJECT INVALID YO");

        return leftOperand * rightOperand;
    }
}

class Day03Parsed : AdventCommon.ParsedInput
{
    public Day03Parsed(string fileName) : base(fileName)
    {

    }

    private int part01 = 0;
    private int part02 = 0;

    private void UpdatePart01(string line)
    {
        string pattern = @"mul\([0-9]{1,3},[0-9]{1,3}\)";

        var m = Regex.Match(line, pattern);

        while (m.Success)
        {
            var mul = new Mul(m.Value);
            part01 += mul.GetResult();

            //Console.WriteLine("'{0}' found at position {1}", m.Value, m.Index);
            m = m.NextMatch();
        }
    }

    private bool UpdatePart02(string line, bool lastMul)
    {
        bool mulEnabled = lastMul;

        SortedDictionary<int, string> ops = new SortedDictionary<int, string>();

        string[] patterns = [
            @"mul\([0-9]{1,3},[0-9]{1,3}\)",
            @"do\(\)",
            @"don't\(\)"
        ];

        foreach (var pattern in patterns)
        {
            for (var r = Regex.Match(line, pattern); r.Success; r = r.NextMatch())
            {
                ops.Add(r.Index, r.Value);
            }
        }

        foreach (var op in ops)
        {
            //Console.WriteLine("{ " + op.Value + " }");

            string canary = "mul(549,60)";
            if (op.Value.Contains(canary))
            {
                //Console.WriteLine("poop");
            }

            if (mulEnabled)
            {
                var m = new Mul(op.Value);

                if (m.IsValid())
                {
                    part02 += m.GetResult();

                   // Console.WriteLine("Added: {0}", m.GetResult());
                    //Console.WriteLine("New: {0}", part02);
                }

                // m not valid, is it a don't?
                if (op.Value.Contains("don't"))
                {
                    //Console.WriteLine("Setting do() to false");
                    mulEnabled = false;
                }
            }
            else
            {
                if (op.Value.Contains("do()"))
                {
                    //Console.WriteLine("Setting do() to true");
                    mulEnabled = true;
                }
            }
        }

        return mulEnabled;
    }

    private bool lastMulEnabled = true;

    public override bool ParseLine(string line, object? context = null)
    {
        UpdatePart01(line);
        
        lastMulEnabled = UpdatePart02(line, lastMulEnabled);

        return true;
    }

    public override int GetPart01()
    {
        return part01;
    }

    public override int GetPart02()
    {
        return part02;
    }
}