2025: d03: ex2: add solution

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()