python(day21): Day 21 woo

python/day21.py

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+import fileinput
+from pprint import pprint
+
+# Parse the input
+foods = []
+all_allergens = set()
+all_ingredients = set()
+for line in fileinput.input():
+    line = line.strip().rstrip(")")
+
+    s = line.split(" (contains ")
+    ingredients = frozenset(s[0].split())
+    allergens = frozenset(s[1].split(", "))
+    all_allergens.update(allergens)
+    all_ingredients.update(ingredients)
+    foods.append((ingredients, allergens))
+
+allergen_ingredients = {allergen: set(all_ingredients) for allergen in all_allergens}
+
+for ingredients, allergens in foods:
+    for allergen in allergens:
+        allergen_ingredients[allergen] &= ingredients
+
+visited_ingredients = set()
+for allergen, ingredients in sorted(
+    allergen_ingredients.items(), key=lambda x: len(x[1])
+):
+    ingredients -= visited_ingredients
+    visited_ingredients |= ingredients
+
+safe_ingredients = set(all_ingredients)
+for _, ingredients in allergen_ingredients.items():
+    safe_ingredients -= ingredients
+
+part1 = 0
+for ingredient in safe_ingredients:
+    part1 += sum((ingredient in ingredients) for ingredients, _ in foods)
+print("part 1:", part1)
+
+dangerous_ingredients = []
+for allergen, ingredients in sorted(allergen_ingredients.items(), key=lambda x: x[0]):
+    dangerous_ingredients.extend(ingredients)
+print("part 2:", ",".join(dangerous_ingredients))