day 11: explore recursively, use cache

d11/run.py

@@ -0,0 +1,21 @@
+import sys
+from math import log10
+from functools import cache
+
+@cache
+def mutate(n:int, t:int) -> int:
+  if t == 0:
+    return 1
+  if n == 0:
+    return mutate(1, t-1)
+  if (digits := int(log10(n))+1) & 1 == 0:
+    return count(divmod(n, 10**(digits//2)), t-1)
+  return mutate(n*2024, t-1)
+
+def count(stones: list[int], times: int) -> int:
+  return sum(mutate(stone, times) for stone in stones)
+
+stones = [int(n) for n in sys.stdin.read().strip().split(" ")]
+
+print(count(stones, 25))
+print(count(stones, 75))