AOC2020D05.py

def get_puzzle_data(a_file_name: str) -> list[str]:
    with open(a_file_name) as INFILE:
        return [line.rstrip() for line in INFILE]

def binary_split(a_front_or_back: str, a_lo: int, a_hi: int) -> tuple[int, int]:
    new_lo: int
    new_hi: int
    range_length = a_hi - a_lo + 1

    if a_front_or_back in 'fFlL':
        new_lo = a_lo
        new_hi = a_lo + (range_length // 2) - 1
    elif a_front_or_back in 'bBrR':
        new_lo = a_lo + (range_length // 2)
        new_hi = a_hi

    return new_lo, new_hi

def get_seating_id(a_boarding_pass: str) -> int:
    seat_id: int = 0

    lo, hi = 0, 127

    for split_type in a_boarding_pass[0:7]:
        lo, hi = binary_split(split_type, lo, hi)

    assert lo == hi, 'Er...'
    seat_row = lo
    # print(f"Row={lo}")

    lo, hi = 0, 7

    for split_type in a_boarding_pass[7:]:
        lo, hi = binary_split(split_type, lo, hi)

    assert lo == hi, 'Er...'
    seat_col = lo
    # print(f"Column={lo}")

    return (8 * seat_row) + seat_col

def get_missing_seat_id(a_boarding_passes: list[str]) -> int:
    missing_seat_id: int = 0

    boarding_pass_seat_ids = [get_seating_id(boarding_pass) for boarding_pass in a_boarding_passes]
    boarding_pass_seat_ids.sort()

    missing_seat_id = [
        seat_id
        for seat_id in boarding_pass_seat_ids
        if ((seat_id + 1 not in boarding_pass_seat_ids
             and seat_id != boarding_pass_seat_ids[-1]))
    ]

    return missing_seat_id[0] + 1

boarding_passes = get_puzzle_data('aoc_2020/aoc_2020_day_05.txt')
# print(f'{boarding_passes=}')

print(f"p1={max([get_seating_id(boarding_pass) for boarding_pass in boarding_passes])}")
print(f"p2={get_missing_seat_id(boarding_passes)}")