AdventOfCode 2018 Day 14

void Main()
{
    #region input
    var testInputA = new string[]
    {
        @"/->-\        ",
        @"|   |  /----\",
        @"| /-+--+-\  |",
        @"| | |  | v  |",
        @"\-+-/  \-+--/",
        @"  \------/   "
    };

    var testInputB = new string[]
    {
        @"/>-<\  ",
        @"|   |  ",
        @"| /<+-\",
        @"| | | v",
        @"\>+</ |",
        @"  |   ^",
        @"  \<->/",
    };
    #endregion

    //tests
    if(AnswerA(testInputA, Part.A) != "7,3") throw new Exception("failed test a1");
    if(AnswerA(testInputB, Part.B) != "6,4") throw new Exception("failed test a2");

    var aoc = new AdventOfCode(2018, 13);
    aoc.SubmitAnswer(AnswerA(aoc.InputLines, Part.A), Part.A);
    aoc.SubmitAnswer(AnswerA(aoc.InputLines, Part.B), Part.B);
}

class Cart
{
    //order of turns
    private static Direction[] intersectionOrder = new[] { Direction.Left, Direction.Straight, Direction.Right, };

    //current position
    public Position<char> position;

    //still oke
    public bool Crashed = false;

    //position
    public int x => position.x;
    public int y => position.y;

    //nextDirection
    private int moveDirection;

    //constructor
    public Cart(int index, Position<char> pos)
    {
        this.position = pos;
        switch (pos.Value)
        {
            case '>': this.position.currentDirection = Direction.East; break;
            case '<': this.position.currentDirection = Direction.West; break;
            case '^': this.position.currentDirection = Direction.North; break;
            case 'v': this.position.currentDirection = Direction.South; break;
            default: throw new NotImplementedException();
        }
    }

    //move
    public void Move()
    {
        //determine direction
        if (this.position.Value == '\\')
        {
            if (this.position.currentDirection == Direction.North || this.position.currentDirection == Direction.South)
                this.position = this.position.Move(Direction.Left);
            else if (this.position.currentDirection == Direction.East || this.position.currentDirection == Direction.West)
                this.position = this.position.Move(Direction.Right);
        }
        else if (this.position.Value == '/')
        {
            if (this.position.currentDirection == Direction.North || this.position.currentDirection == Direction.South)
                this.position = this.position.Move(Direction.Right);
            else if (this.position.currentDirection == Direction.East ||this.position.currentDirection == Direction.West)
                this.position = this.position.Move(Direction.Left);
        }
        //turn
        else if (this.position.Value == '+')
        {
            this.position = this.position.Move(intersectionOrder[moveDirection % 3]);
            moveDirection++;
        }
        //just forward
        else
            this.position = this.position.Move();

    }
}


public string AnswerA(string[] input, Part part)
{
    //create mine
    var mine = Arr2D<char>.FromLines(input);

    //find the starting positions
    var carts = mine.Find(new char[] { '>', '<', '^', 'v' }).Select((x, i) => new Cart(i, x)).ToArray();

    //ui stuff
    //var dc = new DumpContainer().Dump();

    do
    {
        //dcCycle.UpdateContent($"CYCLE: {cycle:D4} \t CARTS: {carts.Length:D2}");
        //dc.UpdateContent(Util.RawHtml(grid.ToHTML(carts.Select(x => x.position))));

        for (int i = 0; i < carts.Length; i++)
        {
            //move each cart
            carts[i].Move();

            //did I move into an occupied space?
            for (int f = 0; f < carts.Length; f++)
            {
                if (i == f) continue; //same cart
                if (carts[i].position.DoesItOverlap(carts[f].position)) //collision
                {
                    if (part == Part.A)
                    {
                        return $"{carts[i].x},{carts[i].y}"; //done
                    }
                    else
                    {
                        //set crashed
                        carts[i].Crashed = true;
                        carts[f].Crashed = true;
                    }
                }
            }
        }
        //reorder and remove crashed
        carts = carts.OrderBy(x => x.y).ThenBy(x => x.x).Where(x => x.Crashed == false).ToArray();
    }while (carts.Length > 1);

    //show last cart
    return $"{carts[0].x},{carts[0].y}";
}