58 lines
1.5 KiB
Python
Executable file
58 lines
1.5 KiB
Python
Executable file
#!/usr/bin/env python
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import itertools
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import sys
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from collections import deque
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from typing import Deque, List, Set, Tuple
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Deck = Deque[int]
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def parse_decks(raw: List[str]) -> Tuple[Deck, Deck]:
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deck_1 = deque(int(n) for n in itertools.takewhile(len, raw[1:]))
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deck_2 = deque(
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int(n) for n in itertools.islice(itertools.dropwhile(len, raw[1:]), 2, None)
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)
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return deck_1, deck_2
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def play(deck_1: Deck, deck_2: Deck) -> Tuple[int, Deck]:
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prev: Set[Tuple[Tuple[int, ...], Tuple[int, ...]]] = set()
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while len(deck_1) and len(deck_2):
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state = (tuple(deck_1), tuple(deck_2))
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if state in prev:
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return 1, deck_1
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prev |= {state}
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left, right = deck_1.popleft(), deck_2.popleft()
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if left <= len(deck_1) and right <= len(deck_2):
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winner, __ = play(deque(list(deck_1)[:left]), deque(list(deck_2)[:right]))
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if winner == 1:
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deck_1.extend((left, right))
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else:
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deck_2.extend((right, left))
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elif left > right:
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deck_1.extend((left, right))
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else:
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deck_2.extend((right, left))
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return (1, deck_1) if len(deck_1) else (2, deck_2)
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def solve(raw: List[str]) -> int:
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__, deck = play(*parse_decks(raw))
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score = sum((i) * val for i, val in enumerate(reversed(deck), 1))
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return score
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def main() -> None:
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input = [line.strip() for line in sys.stdin.readlines()]
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print(solve(input))
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if __name__ == "__main__":
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main()
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