AdventOfCode23/Day21/Vec.cs

namespace Day21;

public record struct Vec
{
    public static Vec Zero { get; } = new Vec(0, 0);
    
    public long X { get; }
    public long Y { get; }

    public bool IsHorizontal => Y == 0;
    public bool IsVertical => X == 0;

    public Vec(long x, long y)
    {
        X = x;
        Y = y;
    }

    public Vec RotatePositive()
    {
        // clockwise
        return new Vec(-1 * Y, X);
    }
    
    public Vec RotateNegative()
    {
        // counter-clockwise
        return new Vec(Y, -1 * X);
    }

    public Vec Add(Vec other)
    {
        return new Vec(X + other.X, Y + other.Y);
    }

    public Vec Multiply(int f)
    {
        return new Vec(f * X, f * Y);
    }

    public long Cross(Vec other)
    {
        return X * other.Y - other.X * Y;
    }

    public static Vec Direction(char c)
    {
        switch (c)
        {
            case 'R':
                return new Vec(1, 0);
            case 'L':
                return new Vec(-1, 0);
            case 'U':
                return new Vec(0, -1);
            case 'D':
                return new Vec(0, 1);
        }

        return default;
    }
}