advent_of_code_2021/day12/part2.py

import argparse
import functools
from collections import defaultdict
from typing import Set, List, Dict

parser = argparse.ArgumentParser()
parser.add_argument("ifile", type=argparse.FileType('r'))
args = parser.parse_args()

graph: defaultdict[str, Set[str]] = defaultdict(set)

for edge in args.ifile.readlines():
    points = edge.strip().split('-')
    graph[points[0]].add(points[1])
    graph[points[1]].add(points[0])


def depthSearch(point, path: List[str], smalls: Set[str], completedPaths: List[List[str]], graph: Dict[str, set[str]], twiced: bool):
    path.extend([point])
    if point == 'end':
        completedPaths.append(path)
        return

    for neighbor in filter(lambda p: p != "start", graph[point]):
        if neighbor.islower():
            if neighbor in smalls:
                if not twiced:
                    depthSearch(neighbor, path, smalls, completedPaths, graph, True)
            else:
                smalls.add(neighbor)
                depthSearch(neighbor, path, smalls, completedPaths, graph, twiced)
                smalls.remove(neighbor)
                path.pop()
        else:
            depthSearch(neighbor, path, smalls, completedPaths, graph, twiced)
            path.pop()


done_paths = []
depthSearch("start", [], set(), done_paths, graph, False)
print(len(done_paths))