"""Solution for 2020/21"""

from functools import reduce

foods = []
all_ingredients = set()
all_allergenes = set()
with open('input', 'r') as f:
    for line in f.readlines():
        [ing, alg] = line.strip(' \n)').split(' (contains ')
        ing = set(ing.split(' '))
        alg = set(alg.split(', '))
        all_ingredients = all_ingredients.union(ing)
        all_allergenes = all_allergenes.union(alg)
        foods.append((ing, alg))

allergeneMap = {}
for ingredients, allergenes in foods:
    for allergene in allergenes:
        if allergene not in allergeneMap:
            allergeneMap[allergene] = ingredients
        else:
            allergeneMap[allergene] = allergeneMap[allergene].intersection(
                ingredients)
print(f'{allergeneMap=}')

allergenic = reduce(lambda x, y: x.union(y), allergeneMap.values())

unallergenic = all_ingredients.difference(allergenic)
print(f'{allergenic=}')
print(f'{unallergenic=}')

ingredientMap = {}
processed = set()
while len(processed) < len(allergenic):
    for allergene, ingredients in allergeneMap.items():
        reduced_ing = ingredients.difference(processed)
        if len(reduced_ing) == 1:
            ing = reduced_ing.pop()
            processed.add(ing)
            ingredientMap[ing] = allergene

print(f'{ingredientMap=}')

sorted_items = sorted(ingredientMap.items(), key=lambda x: x[1])
print(','.join(map(lambda x: x[0], sorted_items)))