From a753c65f2d322cb9c216a5f3d22da067e064f300 Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Wed, 3 Dec 2025 08:19:08 +0000
Subject: [PATCH] 2025: d03: ex2: add solution

---
 2025/d03/ex2/ex2.py | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100755 2025/d03/ex2/ex2.py

diff --git a/2025/d03/ex2/ex2.py b/2025/d03/ex2/ex2.py
new file mode 100755
index 0000000..74dfe88
--- /dev/null
+++ b/2025/d03/ex2/ex2.py
@@ -0,0 +1,35 @@
+#!/usr/bin/env python
+
+import functools
+import sys
+
+
+def solve(input: list[str]) -> int:
+    def parse(input: list[str]) -> list[list[int]]:
+        return [[int(c) for c in line] for line in input]
+
+    def max_joltage(bank: list[int]) -> int:
+        @functools.cache
+        def recurse(bank: tuple[int, ...], length: int) -> int:
+            assert length > 0  # Sanity check
+            assert length <= len(bank)  # Sanity check
+            if length == 1:
+                return max(bank)
+            return max(
+                bank[i] * 10 ** (length - 1) + recurse(bank[i + 1 :], length - 1)
+                for i in range(len(bank) - length + 1)
+            )
+
+        return recurse(tuple(bank), 12)
+
+    batteries = parse(input)
+    return sum(map(max_joltage, batteries))
+
+
+def main() -> None:
+    input = sys.stdin.read().splitlines()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()