73 lines
1.4 KiB
Python
73 lines
1.4 KiB
Python
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def read_file():
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with open("input_sample.txt") as f:
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p1, p2 = f.read().split('\n\n')
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p1 = p1.split('\n')[1:]
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p2 = p2.split('\n')[1:]
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p1 = list(map(int, p1))
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p2 = list(map(int, p2))
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return p1, p2
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def combat(p1,p2):
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while True:
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c1 = p1.pop(0)
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c2 = p2.pop(0)
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if c1 > c2:
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p1 += [c1, c2]
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else:
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p2 += [c2, c1]
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if len(p1) == 0:
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return p2
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if len(p2) == 0:
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return p1
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def part1():
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p1, p2 = read_file()
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winner_deck = combat(p1, p2)
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score = 0
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for i, card in enumerate(reversed(winner_deck)):
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score += (i+1)*card
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return score
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def recursive_combat(p1, p2):
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seen = set()
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while True:
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# does p1 auto-win?
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state = (tuple(p1), tuple(p2))
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if state in seen:
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return 1, p1
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seen.add(state)
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# does anyone win by normal rules?
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if len(p1) == 0:
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return 2, p2
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break
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if len(p2) == 0:
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return 1, p1
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# draw cards
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c1 = p1.pop(0)
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c2 = p2.pop(0)
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# should we recurse?
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if len(p1) >= c1 and len(p2) >= c2: # play recursive round
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winner, deck = recursive_combat(p1[:c1],p2[:c2]) # copy that many cards
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if winner == 1:
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p1 += [c1, c2]
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else: # winner == 2
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p2 += [c2, c1]
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else: # play normal round
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if c1 > c2:
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p1 += [c1, c2]
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else: # c2 > c1
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p2 += [c2, c1]
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def part2():
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p1, p2 = read_file()
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winner, winner_deck = recursive_combat(p1, p2)
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score = 0
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for i, card in enumerate(reversed(winner_deck)):
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score += (i+1)*card
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return score
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def main():
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print(part1(),part2())
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if __name__ == "__main__":
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main()
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