50 lines
1.2 KiB
Python
Executable file
50 lines
1.2 KiB
Python
Executable file
#!/usr/bin/env python
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import functools
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import sys
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from typing import NamedTuple
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class Point(NamedTuple):
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x: int
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y: int
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def solve(input: list[str]) -> int:
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def parse(input: list[str]) -> tuple[Point, set[Point]]:
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start: Point | None = None
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splitters: set[Point] = set()
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for x, line in enumerate(input):
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for y, c in enumerate(line):
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pos = Point(x, y)
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if c == "S":
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start = pos
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elif c == "^":
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splitters.add(pos)
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assert start is not None
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return start, splitters
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def count_timelines(start: Point, splitters: set[Point]) -> int:
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max_x = max(p.x for p in splitters)
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@functools.cache
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def rec(p: Point) -> int:
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if p.x > max_x:
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return 1
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if p not in splitters:
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return rec(Point(p.x + 1, p.y))
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return rec(Point(p.x + 1, p.y - 1)) + rec(Point(p.x + 1, p.y + 1))
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return rec(start)
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start, splitters = parse(input)
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return count_timelines(start, splitters)
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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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