2025: d02: ex2: add solution

2025/d02/ex2/ex2.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python
+
+import math
+import sys
+from collections.abc import Iterator
+
+
+def solve(input: str) -> int:
+    def parse_range(input: str) -> tuple[int, int]:
+        start, end = input.split("-")
+        return int(start), int(end)
+
+    def parse(input: str) -> list[tuple[int, int]]:
+        return [parse_range(r) for r in input.split(",")]
+
+    def iter_invalids(start: int, end: int) -> Iterator[int]:
+        for n in range(start, end):
+            digits = int(math.log10(n)) + 1
+            for repeat in range(2, digits + 1):
+                if digits % repeat != 0:
+                    continue
+                cycle = digits // repeat
+                base = (10**digits - 1) // (10**cycle - 1)
+                if n % base == 0:
+                    yield n
+                    break  # Don't yield the same digit twice
+
+    ranges = parse(input)
+    return sum(sum(iter_invalids(start, end + 1)) for start, end in ranges)
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()