AOC2020D12.py

def get_puzzle_input(a_file_name: str) -> list[str]:
    with open(a_file_name) as INFILE:
        return [line.rstrip() for line in INFILE if not line.startswith('#')]

def get_new_facing(a_currently_facing: str, a_turn_direction: str, a_degrees: int) -> str:
    TURN_LIST = 'NESW' * 3

    currently_facing_idx = TURN_LIST.find(a_currently_facing, 4)
    number_of_turns = a_degrees // 90

    if a_turn_direction == 'L':
        number_of_turns *= -1

    return TURN_LIST[currently_facing_idx + number_of_turns]

def get_new_pos(a_direction: str, a_pos: int, a_distance: str) -> int:
    ret: int = 0

    match a_direction:
        case 'N':
            ret = a_pos + a_distance
        case 'S':
            ret = a_pos - a_distance
        case 'E':
            ret = a_pos + a_distance
        case 'W':
            ret = a_pos - a_distance

    return ret

def solve_p1(a_instructions: list[str]) -> int:

    manhatan: int = 0
    x_coord: int = 0
    y_coord: int = 0
    facing = 'E'

    for instruction in a_instructions:
        move_direction = instruction[0]
        move_distance = int(instruction[1:])

        match move_direction:
            case 'N':
                y_coord = get_new_pos('N', y_coord, move_distance)
            case 'S':
                y_coord = get_new_pos('S', y_coord, move_distance)
            case 'E':
                x_coord = get_new_pos('E', x_coord, move_distance)
            case 'W':
                x_coord = get_new_pos('W', x_coord, move_distance)
            case 'L':
                facing = get_new_facing(facing, 'L', move_distance)
            case 'R':
                facing = get_new_facing(facing, 'R', move_distance)
            case 'F':
                match facing:
                    case 'N':
                        y_coord = get_new_pos('N', y_coord, move_distance)
                    case 'S':
                        y_coord = get_new_pos('S', y_coord, move_distance)
                    case 'W':
                        x_coord = get_new_pos('W', x_coord, move_distance)
                    case 'E':
                        x_coord = get_new_pos('E', x_coord, move_distance)

    return abs(x_coord) + abs(y_coord)

instructions = get_puzzle_input('aoc_2020/aoc_2020_day_12.txt')
# print(f"{instructions=}")

print(f"{solve_p1(instructions)=}")