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