45 lines
1.1 KiB
Python
45 lines
1.1 KiB
Python
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def read_file():
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with open("input.txt","r") as f:
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return list(map(int,list(f.read())))
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def play(cups, rounds):
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current = cups[0]
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next_cup = {c:n for c, n in zip(cups, cups[1:] + [cups[0]])}
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for _ in range(rounds):
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# pickup next 3 cups
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c1 = next_cup[current]
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c2 = next_cup[c1]
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c3 = next_cup[c2]
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# select a destination cup (-1 until found, wraps around)
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destination = current - 1 if current > 1 else len(cups)
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while destination in [c1, c2, c3]:
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destination = destination - 1 if destination > 1 else len(cups)
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# add cups back
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next_cup[current] = next_cup[c3]
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next_cup[c3] = next_cup[destination]
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next_cup[destination] = c1
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# select a new current cup (next)
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current = next_cup[current]
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# rebuild cups from next_cup
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cup = 1
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new_cups = []
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for _ in range(len(cups)):
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cup = next_cup[cup]
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new_cups.append(cup)
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return new_cups
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def part1(cups):
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cups = play(cups, 100)
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return "".join(str(c) for c in cups[:-1])
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def part2(cups):
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cups += list(range(10,1_000_001))
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cups = play(cups,10_000_000)
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return cups[0] * cups[1]
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def main():
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cups = read_file()
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print(part1(cups), part2(cups))
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if __name__ == "__main__":
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main()
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