Solution to day 15, now in python 3.

day-15/input.txt

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+Sugar: capacity 3, durability 0, flavor 0, texture -3, calories 2
+Sprinkles: capacity -3, durability 3, flavor 0, texture 0, calories 9
+Candy: capacity -1, durability 0, flavor 4, texture 0, calories 1
+Chocolate: capacity 0, durability 0, flavor -2, texture 2, calories 8

day-15/solution.py

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+from __future__ import print_function
+import fileinput
+import re
+from operator import mul
+from functools import reduce
+
+pattern = re.compile(r"(\w+): capacity (-?\d+), durability (-?\d+), flavor (-?\d+), texture (-?\d+), calories (-?\d+)")
+
+ingredients = []
+calories = []
+
+def computeScore(amounts):
+    scores = [sum(ingredients[idx][x] * value for idx, value in enumerate(amounts)) for x in range(4)]
+
+    return reduce(mul, [max(x, 0) for x in scores], 1)
+
+def computeCalories(amounts):
+    return sum(a * b for a, b in zip(calories, amounts))
+
+
+def computeMax(ingredient, budget, currentAmounts):
+    budgetLeft = budget - sum(currentAmounts[:ingredient])
+
+    if ingredient == len(ingredients) - 1:
+        currentAmounts[ingredient] = budgetLeft
+        score = computeScore(currentAmounts)
+        if computeCalories(currentAmounts) == 500:
+            return score, score
+
+        return score, None
+
+    results = []
+    resultsCorrect = [0]
+    for n in range(budgetLeft + 1):
+        currentAmounts[ingredient] = n
+        general, correct = computeMax(ingredient + 1, budget, currentAmounts)
+        results.append(general)
+        resultsCorrect.append(correct)
+
+    return max(results), max(x for x in resultsCorrect if x is not None)
+
+for line in fileinput.input():
+    match = pattern.match(line)
+    ingredients.append([int(x) for x in match.group(2, 3, 4, 5)])
+    calories.append(int(match.group(6)))
+
+print(computeMax(0, 100, [0] * len(ingredients)))