34 lines
792 B
Python
34 lines
792 B
Python
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#!/usr/bin/env python
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import sys
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import itertools
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Report = list[int]
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def solve(input: list[str]) -> int:
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def parse(input: list[str]) -> list[Report]:
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return [[int(n) for n in line.split()] for line in input]
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def is_safe(report: Report) -> bool:
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def is_increasing_safe(report: Report):
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for a, b in itertools.pairwise(report):
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if a >= b:
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return False
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if not 1 <= (b - a) <= 3:
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return False
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return True
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return is_increasing_safe(report) or is_increasing_safe(report[::-1])
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return sum(is_safe(report) for report in parse(input))
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def main() -> None:
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input = sys.stdin.read().splitlines()
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print(solve(input))
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if __name__ == "__main__":
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main()
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