Solve 2024 day 11

2024/d11.py

@@ -0,0 +1,31 @@
+from lib import get_data
+from lib import ints
+
+data = get_data(__file__)
+xs = ints(data)
+CACHE = {}
+
+# I had maxsize too small at first :/
+# @lru_cache(maxsize=10**12) 
+def apply(x, rest):
+    if rest == 0:
+        return 1
+
+    if (x, rest) in CACHE:
+        return CACHE[(x, rest)]
+
+    if x == 0:
+        r = apply(1, rest - 1)
+    elif len(str(x)) % 2 == 0:
+        sx = str(x)
+        a = int(sx[: len(sx) // 2])
+        b = int(sx[len(sx) // 2 :])
+        r = apply(a, rest - 1) + apply(b, rest - 1)
+    else:
+        r = apply(x * 2024, rest - 1)
+    CACHE[(x, rest)] = r
+    return r
+
+
+print(sum([apply(x, 25) for x in xs]))
+print(sum([apply(x, 75) for x in xs]))

README.md

@@ -301,4 +301,6 @@ and focus. Of course, learning more algorithms and techniques helps.
 - Day  8: `00:15:59  1742      0   00:26:56  2190      0`
 - Day  9: `00:48:23  6055      0   01:09:38  3159      0`
 - Day 10: `00:19:47  2976      0   00:20:47  2244      0`
+- Day 11: `11   00:05:13   642      0   00:33:07  2673      0`
+