day11a.py

from collections import defaultdict

f = open('input.txt', 'r')
lines = [line.split(' ') for line in f.read().split('\n')]

neighs = defaultdict(list)
neighs |= {line[0][:-1]: line[1:] for line in lines}

nodes = list(set(list(neighs.keys())))
nodes = list(set(nodes + [node for vals in neighs.values() for node in vals]))


in_edges = defaultdict(int)
for key, values in neighs.items():
	for neigh in values:
		in_edges[neigh] += 1

count = defaultdict(int)
count['you'] = 1

q = [node for node in nodes if in_edges[node] == 0]
while q:
	curr = q.pop()
	for neigh in neighs[curr]:
		in_edges[neigh] -= 1
		count[neigh] += count[curr]

		if in_edges[neigh] == 0:
			q.append(neigh)

print(count['out'])