Add solution to 2024-12-22

Author: fuglede

2024/day22/solutions.py

@@ -0,0 +1,32 @@
+from collections import defaultdict
+import numpy as np
+
+with open("input") as f:
+    ns = list(map(int, f.read().strip().split("\n")))
+
+
+def hsh(secret):
+    for _ in range(2000):
+        secret ^= secret << 6 & 0xFFFFFF
+        secret ^= secret >> 5 & 0xFFFFFF
+        secret ^= secret << 11 & 0xFFFFFF
+        yield secret
+
+
+secrets = list(map(list, map(hsh, ns)))
+
+# Part 1
+print(sum(s[-1] for s in secrets))
+
+# Part 2
+result = defaultdict(int)
+for n in ns:
+    ss = [s % 10 for s in hsh(n)]
+    diffs = np.diff(ss)
+    changes = set()
+    for i in range(1996):
+        if (change := tuple(diffs[i : i + 4])) not in changes:
+            changes.add(change)
+            result[change] += ss[i + 4]
+
+print(max(result.values()))