AdventOfCode2025/AdventOfCode2025/Day3.cs

using AdventOfCode2025.Inputs;

namespace AdventOfCode2025;

public class Day3 : Solution
{
    private readonly Input input = new(3);

    public override string SolvePart1() => input.GetLines(x => ParseLine(x, 2)).Sum().ToString();

    public override string SolvePart2() => input.GetLines(x => ParseLine(x, 12)).Sum().ToString();

    private static long GetLargestJolts(int[] bank, int numberOfJolts = 2)
    {
        var total = 0L;
        var from = 0;
        int to = bank.Length - numberOfJolts;
        for (int i = numberOfJolts - 1; i >= 0; i--)
        {
            int maxIndexI = GetIndexOfMax(bank, from, to);
            total += bank[maxIndexI] * (long)Math.Pow(10, i);
            from = maxIndexI + 1;
            to = bank.Length - i;
        }

        return total;
    }

    // private int GetLargestJolts(int[] bank)
    // {
    //     var maxIndex10 = GetIndexOfMax(bank, 0, bank.Length-1);
    //     var maxIndex1 = GetIndexOfMax(bank, maxIndex10+1, bank.Length);
    //     var t = bank[maxIndex10] * 10 + bank[maxIndex1];
    //     return t;
    // }

    private static int GetIndexOfMax(int[] array, int from, int to)
    {
        int maxIndex = from;
        if (from + 1 > to)
        {
            return maxIndex;
        }

        for (int i = from + 1; i <= to; i++)
        {
            if (array[i] > array[maxIndex])
            {
                maxIndex = i;
            }
        }

        return maxIndex;
    }

    private static long ParseLine(string line, int numberOfJolts)
    {
        int[] bank = line.Select(c => c - '0').ToArray();
        return GetLargestJolts(bank, numberOfJolts);
    }
}