Day 4: Scratchcards

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  • @UlrikHD@programming.devEnglish
    2•1 year ago

    Feels like the challenges are getting easier than harder currently. Fairly straightforward when doing it the lazy way with python.

    Python 
    import re

winning_number_pattern: re.Pattern = re.compile(r' +([\d ]*?) +\|')
lottery_number_pattern: re.Pattern = re.compile(r'\| +([\d ]*)')


def get_winning_numbers(line: str) -> set[str]:
    return set(winning_number_pattern.search(line).group(1).split())


def get_lottery_numbers(line: str) -> set[str]:
    return set(lottery_number_pattern.search(line).group(1).split())


def get_winnings(winning_numbers: set[str], lottery_numbers: set[str]) -> int:
    return int(2 ** (len(winning_numbers.intersection(lottery_numbers)) - 1))


def puzzle_1() -> int:
    points: int = 0
    with open('day4_scratchcards.txt', 'r', encoding='utf-8') as file:
        for line in file:
            points += get_winnings(get_winning_numbers(line), get_lottery_numbers(line))
    return points


class ScratchCard:
    def __init__(self, line: str):
        self.amount: int = 1
        self.winnings: int = len(get_winning_numbers(line).intersection(get_lottery_numbers(line)))

    def update(self, extra: int) -> None:
        self.amount = self.amount + extra

    def __radd__(self, other):
        return self.amount + other


def puzzle_2() -> int:
    scratch_card_list: list[ScratchCard] = []
    with open('day4_scratchcards.txt', 'r', encoding='utf-8') as file:
        for line in file:
            scratch_card_list.append(ScratchCard(line))

    for i, scratch_card in enumerate(scratch_card_list):
        for j in range(1, scratch_card.winnings + 1):
            try:
                scratch_card_list[i + j].update(scratch_card.amount)
            except IndexError:
                pass
    return sum(scratch_card_list)


if __name__ == '__main__':
    print(puzzle_1())
    print(puzzle_2())
    • @bob_lemon@feddit.de
      1•1 year ago

      That int-call on the return value for the point value is a good idea. I manually returned 0 if there were no matches.

      • @UlrikHD@programming.dev
        1•1 year ago

        I personally would prefer the if check and return 0 in most instances just because it’s clearer and more readable. But the two previous functions were one-liners so it just looked better if get_winnings() also was.

    • Leo Uino
      1•1 year ago

      Puzzles on the weekend are usually a bit more involved than weekdays. 23 is probably going to be a monster this year…