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45 lines
1.0 KiB
Python
45 lines
1.0 KiB
Python
from typing import List, TextIO
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def shuffle(instructions: List[str], deck_size: int) -> List[int]:
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deck = list(range(0, deck_size))
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for instruction in instructions:
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if "new stack" in instruction:
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deck = list(reversed(deck))
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continue
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parts = instruction.split(" ")
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if parts[0] == "cut":
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by = int(parts[1])
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new_deck = deck[by:]
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new_deck += deck[:by]
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deck = new_deck
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else:
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increment = int(parts[3])
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new_deck = list(range(0, deck_size))
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target_index = 0
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for card in deck:
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new_deck[target_index] = card
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target_index = (target_index + increment) % len(deck)
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deck = new_deck
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return deck
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def part1(data: TextIO):
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instructions = [line.strip() for line in data]
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result = shuffle(instructions, 10007)
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for i, card in enumerate(result):
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if card == 2019:
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return i
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raise Exception("Did not find card")
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