50 lines
1.1 KiB
Python
Executable file
50 lines
1.1 KiB
Python
Executable file
#!/usr/bin/env python
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import itertools
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import sys
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from collections import defaultdict
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from typing import Dict, List, Set
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Map = Dict[str, Set[str]]
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def solve(input: List[str]) -> int:
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def parse() -> Map:
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res: Map = defaultdict(set)
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for start, to in map(lambda s: s.split("-"), input):
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res[start].add(to)
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res[to].add(start)
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return res
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caves = parse()
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def dfs(start: str, seen: Set[str] = set(), has_doubled_back: bool = False) -> int:
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if start == "end":
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return 1
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seen = seen | {start}
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res = 0
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for dest in caves[start]:
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doubles_back = False
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if dest in seen and dest.islower():
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if has_doubled_back or dest == "start":
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continue
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doubles_back = True
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res += dfs(dest, seen, has_doubled_back or doubles_back)
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return res
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return dfs("start")
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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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