58 lines
1.8 KiB
Python
58 lines
1.8 KiB
Python
# SPDX-License-Identifier: MIT
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# Copyright (c) 2021 Akumatic
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#
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# https://adventofcode.com/2021/day/12
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def add_to_dict(d: dict, key: str, value: str):
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if key not in d:
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d[key] = [value]
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else:
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d[key].append(value)
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def parse_paths(connections: list):
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paths = dict()
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for connection in connections:
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tmp = connection.split("-")
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add_to_dict(paths, tmp[0], tmp[1])
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add_to_dict(paths, tmp[1], tmp[0])
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return paths
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def read_file(filename: str = "input.txt") -> list:
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with open(f"{__file__.rstrip('code.py')}{filename}", "r") as f:
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return [line for line in f.read().strip().split("\n")]
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def part1(paths: dict) -> int:
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complete = list()
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incomplete = [["start"]]
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while incomplete:
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previous = incomplete.pop()
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for next_step in paths[previous[-1]]:
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if next_step.lower() not in previous:
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p = previous[:]
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p.append(next_step)
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complete.append(p) if next_step == "end" else incomplete.append(p)
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return len(complete)
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def part2(paths: dict) -> int:
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complete = list()
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incomplete = [["start"]]
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small = [x for x in paths if x.islower() and x != "end" and x != "start"]
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while incomplete:
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previous = incomplete.pop()
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for next_step in paths[previous[-1]]:
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if next_step == "start":
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continue
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if next_step in small:
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if next_step in previous and any(previous.count(x) > 1 for x in small):
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continue
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p = previous[:]
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p.append(next_step)
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complete.append(p) if next_step == "end" else incomplete.append(p)
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return len(complete)
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if __name__ == "__main__":
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vals = read_file()
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paths = parse_paths(vals)
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print(f"Part 1: {part1(paths)}")
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print(f"Part 2: {part2(paths)}")
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