Day 4: Scratchcards


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  • __init__@programming.dev
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    11 months ago

    (python) Much easier than day 3.

    code
    import pathlib
    
    base_dir = pathlib.Path(__file__).parent
    filename = base_dir / "day4_input.txt"
    
    with open(base_dir / filename) as f:
        lines = f.read().splitlines()
    
    score = 0
    
    extra_cards = [0 for _ in lines]
    n_cards = [1 for _ in lines]
    
    for i, line in enumerate(lines):
        _, numbers = line.split(":")
        winning, have = numbers.split(" | ")
    
        winning_numbers = {int(n) for n in winning.split()}
        have_numbers = {int(n) for n in have.split()}
    
        have_winning_numbers = winning_numbers & have_numbers
        n_matches = len(have_winning_numbers)
    
        if n_matches:
            score += 2 ** (n_matches - 1)
    
        j = i + 1
        for _ in range(n_matches):
            if j >= len(lines):
                break
            n_cards[j] += n_cards[i]
            j += 1
    
    answer_p1 = score
    print(f"{answer_p1=}")
    
    answer_p2 = sum(n_cards)
    print(f"{answer_p2=}")