AdventOfCode23/Day17/Map.cs

namespace Day17;

public class Map
{
    private readonly Tile[,] _tiles;
    private readonly int _width;
    private readonly int _height;

    public Map(Tile[,] tiles, int width, int height)
    {
        _tiles = tiles;
        _width = width;
        _height = height;
    }

    public void Print()
    {
        for (var y = 0; y < _height; y++)
        {
            for (var x = 0; x < _width; x++)
            {
                Console.Write(_tiles[x, y].Display);
            }

            Console.WriteLine();
        }

        Console.WriteLine();
    }

    public int ShortestPath()
    {
        var n = 0;
        var goal = _tiles[_width - 1, _height - 1];
        var visited = new HashSet<string>();
        var queue = new PriorityQueue<Path, int>();
        queue.Enqueue(new Path(null, _tiles[0, 0], new Vec(1, 0)), 0);
        queue.Enqueue(new Path(null, _tiles[0, 0], new Vec(0, 1)), 0);

        while (queue.Count > 0)
        {
            var current = queue.Dequeue();
            var curKey = current.GetKey();
            if (!visited.Add(curKey))
            {
                continue;
            }

            foreach (var v in current.Next())
            {
                var pos = current.Tile.Position.Add(v);
                if (IsValid(pos))
                {
                    var next = new Path(current, Tile(pos), v);
                    if (next.Tile == goal)
                    {
                        var cost = Backtrack(next);
                        return cost;
                    }
                    queue.Enqueue(next, next.Cost);
                }
            }

            if (n % 100 == 0)
            {
                Console.WriteLine($"Queue: {queue.Count}");
            }
            n++;
        }

        return -1;
    }

    private int Backtrack(Path path)
    {
        var sum = 0;
        while (path.Prev != null)
        {
            sum += path.Tile.Cost;
            path.Tile.SetDisplay(path.VRun.Arrow());
            path = path.Prev;
        }

        return sum;
    }

    private bool IsValid(Vec position)
    {
        return position.X >= 0 && position.X < _width && position.Y >= 0 && position.Y < _height;
    }

    private Tile Tile(Vec position)
    {
        return _tiles[position.X, position.Y];
    }
}