AdventOfCode/AdventOfCode.Solutions/2024/Day 06/Day06.cs

using AdventOfCode.Core.Shared.IO;

namespace AdventOfCode.Solutions._2024
{
    public class Day06 : IChallange
    {
        public int Year => 2024;

        public int Day => 6;

        private readonly IInputReader _inputReader;

        public Day06(IInputReader inputReader)
        {
            _inputReader = inputReader;
            _inputReader.SetInput(this);
            //_inputReader.SetSampleInput(true);
        }

        // 41
        // 4696
        public async Task<string> GetSolutionPart1()
        {
            Grid<Point> map = await _inputReader.ReadToGrid<Point>();
            Point current = map.DataGrid.Single(p => p.Value == '^');
            HashSet<Point> points = [current];
            Point move = new Point(0, -1);

            do
            {
                // check if we are done
                long nextX = current.X + move.X,
                    nextY = current.Y + move.Y;
                if (nextX == -1 || nextX == map.Columns
                    || nextY == -1 || nextY == map.Rows)
                    break;

                // get next
                Point next = map.GetNode(nextX, nextY);
                if (next.Value == '#')
                {
                    move = Turn(move);
                    //Console.WriteLine("turned " + move.ToString());
                    continue;
                }

                points.Add(next);
                current = next;
                //Console.WriteLine("moved " + current.ToString());
            }
            while (true);

            return points.Count.ToString();
        }

        // 6
        // 
        public async Task<string> GetSolutionPart2()
        {
            return string.Empty;
        }

        private Point Turn(Point currentDir)
        {
            if (currentDir.Y == -1 && currentDir.X == 0)
            {
                currentDir.Y = 0;
                currentDir.X = 1;
                return currentDir;
            }
            else if (currentDir.Y == 0 && currentDir.X == 1)
            {
                currentDir.Y = 1;
                currentDir.X = 0;
                return currentDir;
            }
            else if (currentDir.Y == 1 && currentDir.X == 0)
            {
                currentDir.Y = 0;
                currentDir.X = -1;
                return currentDir;
            }
            else if(currentDir.Y == 0 && currentDir.X == -1)
            {
                currentDir.Y = -1;
                currentDir.X = 0;
                return currentDir;
            }

            throw new InvalidDataException();
        }
    }
}