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"""Day 7."""
import re
from collections import defaultdict
pattern = r"(\d+) ([a-z]+) ([a-z]+) (bag[s]?)"
prog = re.compile(pattern)
with open("input") as f:
sections = f.read().rstrip().split("\n")
mapping = defaultdict(lambda: [])
# Put bags into dict structure
for section in sections:
parent, child_str = section.split(" bags contain ")
children = []
if "no other bags" not in child_str:
for child in child_str.replace(".", "").split(", "):
_, adjective, color, _ = prog.match(child).groups()
children.append(f"{adjective} {color}")
for child in children:
mapping[child].append(parent)
# Part 1
bags = set(mapping['shiny gold'])
while True:
new_bags = bags.copy()
for bag in bags:
for new_bag in mapping[bag]:
new_bags.add(new_bag)
if len(new_bags) == len(bags):
print(len(bags))
break
else:
bags = new_bags
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