AdventOfCode2021_Day2

public static Command[] Commands;
public static Submarine Submarine;

public static void ProcessInput(string[] lines)
{
    Commands = new Command[lines.Length];
    for (int i = 0; i < lines.Length; i++)
    {
        string[] words = lines[i].Split();
        Commands[i].Direction = words[0];
        Commands[i].Units = int.Parse(words[1]);
    }
}

public static int SolveP1()
{
    Submarine = new Submarine(Position.zero);
    for (int i = 0; i < Commands.Length; i++)
    {
        if (Commands[i].Direction == "forward")
        {
            Submarine.Position.Horizontal += Commands[i].Units;
        }
        else if (Commands[i].Direction == "up")
        {
            Submarine.Position.Depth -= Commands[i].Units;
        }
        else if (Commands[i].Direction == "down")
        {
            Submarine.Position.Depth += Commands[i].Units;
        }
    }
    return Submarine.Position.Horizontal * Submarine.Position.Depth;
}

public static int SolveP2()
{
    Submarine = new Submarine(Position.zero);
    for (int i = 0; i < Commands.Length; i++)
    {
        if (Commands[i].Direction == "forward")
        {
            Submarine.Position.Horizontal += Commands[i].Units;
            Submarine.Position.Depth += Submarine.Aim * Commands[i].Units;
        }
        else if (Commands[i].Direction == "up")
        {
            Submarine.Aim -= Commands[i].Units;
        }
        else if (Commands[i].Direction == "down")
        {
            Submarine.Aim += Commands[i].Units;
        }
    }
    return Submarine.Position.Horizontal * Submarine.Position.Depth;
}

public struct Position
{
    public int Horizontal;
    public int Depth;

    public static Position zero = new Position();

    public Position(int horizontal = 0, int depth = 0)
    {
        Horizontal = horizontal;
        Depth = depth;
    }

    public static Position operator +(Position p1, Position p2)
    {
        return new Position
        {
            Depth = p1.Depth + p2.Depth,
            Horizontal = p1.Horizontal + p2.Horizontal
            };
    }
    public static Position operator -(Position p1, Position p2)
    {
        return new Position
        {
            Depth = p1.Depth - p2.Depth,
            Horizontal = p1.Horizontal - p2.Horizontal
            };
    }
    public static Position operator *(Position p, int num)
    {
        return new Position
        {
            Depth = p.Depth * num,
            Horizontal = p.Horizontal * num
            };
    }
}

public struct Command
{
    public string Direction;
    public int Units;
}