42 lines
1 KiB
Python
Executable file
42 lines
1 KiB
Python
Executable file
#!/usr/bin/env python
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import functools
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import itertools
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import math
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import sys
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def solve(input: list[str]) -> int:
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def parse(input: list[str]) -> dict[str, set[str]]:
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return {
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dev: set(outputs.split(" "))
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for dev, outputs in map(lambda s: s.split(": "), input)
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}
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def count_paths(graph: dict[str, set[str]], start: str, end: str) -> int:
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@functools.cache
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def rec(start: str, end: str) -> int:
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if start == end:
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return 1
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return sum(rec(n, end) for n in graph.get(start, []))
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# Input is assured to be a DAG, so a simple recursive count is enough
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return rec(start, end)
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graph = parse(input)
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return sum(
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math.prod(count_paths(graph, a, b) for a, b in itertools.pairwise(path))
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for path in (
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["svr", "dac", "fft", "out"],
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["svr", "fft", "dac", "out"],
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)
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)
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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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