ud

r0f1 · r0f1 · commit bbb62afb602a · 2020-12-25T19:05:44.000+01:00
diff --git a/day21/main.py b/day21/main.py
@@ -0,0 +1,41 @@
+from collections import defaultdict
+
+import numpy as np
+from more_itertools import flatten
+
+with open("input.txt") as f:
+    lines = [x.strip() for x in f]
+
+foods     = [x.split(" (contains ")[0].split() for x in lines]
+allergens = [x.split(" (contains ")[1][:-1].split(", ") for x in lines]
+recipe    = list(zip(foods, allergens))
+
+poss_allergens = sorted(set(list(flatten(allergens))))
+
+poss = []
+for _, pa in enumerate(poss_allergens):
+    k = []
+    for fs, allergs in recipe:
+        if pa in allergs:
+            k.append(set(fs))
+    poss.append(k)
+
+reduced = [set.intersection(*ps) for ps in poss]
+remaining_foods = sorted(set(flatten(reduced)))
+count = len([f for f in flatten(foods) if f not in remaining_foods])
+print(count)
+poss_mat = np.array([[1 if r in red else 0 for r in remaining_foods] for red in reduced])
+
+change = True
+seen = set()
+while change:
+    change = False
+    for i, row in enumerate(poss_mat):
+        if sum(row) == 1 and i not in seen:
+            seen.add(i)
+            change = True
+            col = np.argmax(row)
+            poss_mat[:, col] = 0
+            poss_mat[i, col] = 1
+
+print(",".join(remaining_foods[np.argmax(poss_mat[i])] for i in range(len(remaining_foods))))
