42 lines
847 B
Python
Executable file
42 lines
847 B
Python
Executable file
#!/usr/bin/env python
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import sys
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from typing import List
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def seat_id(boarding_pass: str) -> int:
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min_x = 0
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max_x = 128
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min_y = 0
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max_y = 8
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for char in boarding_pass:
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if char == "F":
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max_x = (min_x + max_x) // 2
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elif char == "B":
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min_x = (min_x + max_x) // 2
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elif char == "L":
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max_y = (min_y + max_y) // 2
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elif char == "R":
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min_y = (min_y + max_y) // 2
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return min_x * 8 + min_y
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def solve(passes: List[str]) -> int:
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ids = sorted(seat_id(p) for p in passes)
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for prev, cur in zip(ids, ids[1:]):
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if prev + 1 != cur:
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return prev + 1
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assert False # Sanity check
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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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