Solve 2021 day 6

2021/d6.py

@@ -0,0 +1,32 @@
+from lib import get_data
+from lib import ints
+from collections import defaultdict
+
+data = get_data(__file__).strip()
+xs = ints(data)
+
+for _ in range(80):
+    for i in range(len(xs)):
+        if xs[i] == 0:
+            xs[i] = 6
+            xs.append(8)
+        else:
+            xs[i] -= 1
+
+print(len(xs))
+
+xs = ints(data)
+fish = defaultdict(int)
+for x in xs:
+    fish[x] += 1
+
+for _ in range(256):
+    new_fish = defaultdict(int)
+    new_fish[8] = fish[0]
+    new_fish[6] = fish[0]
+    for i in range(1, 9):
+        new_fish[i - 1] += fish[i]
+    fish = new_fish
+
+r = sum(fish.values())
+print(r)