AdventOfCode23/Day17/Path.cs

namespace Day17;

public class Path
{
    public Path? Prev { get; }
    public Tile Tile { get; }
    public Vec VRun { get; }
    public int LRun { get; }
    public int Cost { get; }
    
    public Path(Path? prev, Tile tile, Vec vRun)
    {
        Prev = prev;
        Tile = tile;
        
        VRun = vRun;
        LRun = prev == null
            ? 0
            : vRun == Prev?.VRun ? Prev!.LRun + 1 : 1;

        Cost = (prev?.Cost ?? 0) + tile.Cost;
    }

    public virtual IEnumerable<Vec> Next()
    {
        yield return VRun.RotatePositive();
        if (LRun < 3)
        {
            yield return VRun;
        }
        yield return VRun.RotateNegative();
    }

    public virtual bool CanStop()
    {
        return true;
    }

    public string GetKey()
    {
        return $"{Tile.Position.X}/{Tile.Position.Y},{VRun.X}/{VRun.Y},{LRun}";
    }
}