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☃️ - 2023 DAY 4 SOLUTIONS -☃️

Day 4: Scratchcards


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

      • 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.

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

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