2018: d02: ex1: add solution

2018/d02/ex1/ex1.py

@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+
+import sys
+from collections import Counter
+
+
+def solve(input: str) -> int:
+    def any_letter(boxes: list[str], count: int) -> int:
+        return sum(count in Counter(box).values() for box in boxes)
+
+    def checksum(boxes: list[str]) -> int:
+        return any_letter(boxes, 2) * any_letter(boxes, 3)
+
+    boxes = input.splitlines()
+    return checksum(boxes)
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()