AdventOfCode/AdventOfCode.Solutions/2023/Day 13/Day13.cs

using AdventOfCode.Core;
using AdventOfCode.Solutions._2023.Day_13;
using System.Data;

namespace AdventOfCode.Solutions._2023
{
    public class Day13(InputReader reader) : IChallange
    {
        private InputReader _inputReader = reader;

        public async Task<string> GetSolutionPart1()
        {
            int rowMirrors = 0, columnMirrors = 0;
            await foreach (Grid<Node> map in _inputReader.ReadToGrids<Node>())
            {
                (List<string> rows, List<string> columns) = map.GetRowsAndColumns();
                int r = 0, c = 0;
                r = GetReflectedRow(rows, false);
                rowMirrors += r;
                if (r == 0)
                {
                    c = GetReflectedRow(columns, false);
                    columnMirrors += c;
                }
            }

            return (rowMirrors * 100 + columnMirrors).ToString();
        }

        public async Task<string> GetSolutionPart2()
        {
            int rowMirrors = 0, columnMirrors = 0;
            await foreach (Grid<Node> map in _inputReader.ReadToGrids<Node>())
            {
                (List<string> rows, List<string> columns) = map.GetRowsAndColumns();
                int r = 0, c = 0;
                r = GetReflectedRow(rows, true);
                rowMirrors += r;
                if (r == 0)
                {
                    c = GetReflectedRow(columns, true);
                    columnMirrors += c;
                }
            }

            return (rowMirrors * 100 + columnMirrors).ToString();
        }

        private static int GetReflectedRow(List<string> lines, bool derectSmudge = false)
        {
            for (var rowIndex = 0; rowIndex < lines.Count - 1; rowIndex++)
            {
                bool foundMirrors = false, foundSmudge = false;
                for (var charIndex = 0; charIndex < lines[rowIndex].Length; charIndex++)
                {
                    for (var smudge = 0; smudge <= Math.Min(rowIndex, lines.Count - 2 - rowIndex); smudge++)
                    {
                        if (lines[rowIndex - smudge][charIndex] != lines[rowIndex + 1 + smudge][charIndex])
                        {
                            if (derectSmudge && !foundSmudge)
                            {
                                foundSmudge = true;
                            }
                            else
                            {
                                foundMirrors = true;
                                break;
                            }
                        }
                    }

                    if (foundMirrors)
                    {
                        break;
                    }
                }

                if (derectSmudge && !foundSmudge)
                {
                    // continue to find the damn thing
                    continue;
                }

                if (!foundMirrors)
                { 
                    return rowIndex + 1;
                }
            }

            return 0;
        }

    }
}