/
day21.py
42 lines (32 loc) · 1.08 KB
/
day21.py
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from collections import Counter
from aocd.models import Puzzle
input: str = Puzzle(day=21, year=2020).input_data
ingredient_counter = Counter()
alergen2ingredients = {}
for food in input.splitlines():
ingredients, alergens = food.split(" (contains ")
ingredients = ingredients.split()
alergens = alergens[:-1].split(", ")
ingredient_counter.update(ingredients)
for alergen in alergens:
if alergen in alergen2ingredients:
alergen2ingredients[alergen] &= set(ingredients)
else:
alergen2ingredients[alergen] = set(ingredients)
singles = set()
while len(singles) != len(alergen2ingredients):
for alg, ings in alergen2ingredients.items():
if len(ings) == 1:
singles |= ings
else:
ings -= singles
def part1():
return sum(
count
for ingredient, count in ingredient_counter.items()
if ingredient not in set.union(*alergen2ingredients.values())
)
def part2():
return ",".join(
alergen2ingredients[alergen].pop() for alergen in sorted(alergen2ingredients)
)