string[] input = File.ReadAllLines(@"C:\Users\*\Advent of Code\2023\Day16\Day16Input.txt");

string[] test = File.ReadAllLines(@"C:\Users\*\Advent of Code\2023\Day16\Day16Test.txt");

​

//Console.WriteLine("Part One (test): " + Solver(test));

Console.WriteLine("Part One: " + Solver(input));

​

int Solver(string[] input)

{

    Dictionary<Coordinates, char> grid = new();

    List<Coordinates> litCoordinates = new();

    List<State> seen = new();

    Coordinates start = new(0, 0);

    string direction = "EAST"; 

    litCoordinates.Add(start);

​

    int maxRow = input.Length;

    int maxCol = input[0].Length;

​

    for (int row = 0; row < input.Length; row++)

    {

        for (int col = 0; col < input[0].Length; col++)

        {

            grid[new Coordinates(col, row)] = input[row][col];

        }

    }

​

    Queue<State> lightBranches = new();

    lightBranches.Enqueue(new State(direction, litCoordinates[0]));

​

    while (lightBranches.TryDequeue(out State prevSpace))

    {

        if (seen.Contains(prevSpace)) continue;

​

        (direction, start) = prevSpace;

​

        Coordinates nextSpace = NestSpace(direction, start);

​

        if (nextSpace.Row < 0 || nextSpace.Column < 0 || nextSpace.Row >= maxRow || nextSpace.Column >= maxCol)

        {

            continue;

        }

​

        if (!litCoordinates.Contains(nextSpace)) litCoordinates.Add(nextSpace);

​

        switch (grid[nextSpace])

        {

            case '|':

                if (direction == "EAST" || direction == "WEST")

                {

                    lightBranches.Enqueue(new State("NORTH", nextSpace));

                    lightBranches.Enqueue(new State("SOUTH", nextSpace));

                }

                else lightBranches.Enqueue(new State(direction, nextSpace));

                break;

​

            case '-':

                if (direction == "NORTH" || direction == "SOUTH")

                {

                    lightBranches.Enqueue(new State("EAST", nextSpace));

                    lightBranches.Enqueue(new State("WEST", nextSpace));

                }

                else lightBranches.Enqueue(new State(direction, nextSpace));

                break;

​

            case '/':

                if (direction == "NORTH") //North >> East

                {

                    direction = "EAST";

                }

                else if (direction == "EAST") //East >> North

                {

                    direction = "NORTH";

                }

                else if (direction == "WEST") //West >> South

                {

                    direction = "SOUTH";

                }

                else if (direction == "SOUTH") //South >> West

                {

                    direction = "WEST";

                }

                lightBranches.Enqueue(new State(direction, nextSpace));

                break;

​

            case '\\':

                if (direction == "NORTH") //North >> West

                {

                    direction = "WEST";

                }

                else if (direction == "EAST") //East >> South

                {

                    direction = "SOUTH";

                }

                else if (direction == "WEST") //West >> North

                {

                    direction = "NORTH";

                }

                else if (direction == "SOUTH") //South >> East

                {

                    direction = "EAST";

                }

                lightBranches.Enqueue(new State(direction, nextSpace));

                break;

​

            default:

                lightBranches.Enqueue(new State(direction, nextSpace));

                break;

        }

​

        seen.Add(prevSpace);

    }

​

    for (int row = 0; row < input.Length; row++)

    {

        int rowcount = 0;

​

        for (int col = 0; col < input[0].Length; col++)

        {

            if (litCoordinates.Contains(new Coordinates(col, row)))

            {

                rowcount++;

            }

        }

​

        Console.WriteLine("Row {0} \t Contains {1}", row, rowcount);

    }

​

    return litCoordinates.Count;

}

​

Coordinates NestSpace(string direction, Coordinates start)

{

    int row = start.Row;

    int col = start.Column;

​

    switch (direction)

    {

        case "NORTH":

            row--;

            break;

        case "EAST":

            col++;

            break;

        case "SOUTH":

            row++;

            break;

        case "WEST":

            col--;

            break;

    }

​

    return new Coordinates(col, row);

}

​

record Coordinates(int Column, int Row);

record State(string Direction, Coordinates Coordinates);