2015: d05: ex2: add solution

2015/d05/ex2/ex2.py

@@ -0,0 +1,42 @@
+#!/usr/bin/env python
+
+import collections
+import itertools
+import sys
+from collections.abc import Iterable, Iterator
+from typing import TypeVar
+
+T = TypeVar("T")
+
+
+def sliding_window(iterable: Iterable[T], n: int) -> Iterator[tuple[T, ...]]:
+    iterator = iter(iterable)
+    window = collections.deque(itertools.islice(iterator, n - 1), maxlen=n)
+    for x in iterator:
+        window.append(x)
+        yield tuple(window)
+
+
+def solve(input: str) -> int:
+    def is_nice(input: str) -> bool:
+        if not any(
+            ab in rest
+            for ab, rest in (
+                (input[i : i + 2], input[i + 2 :]) for i in range(len(input) - 1)
+            )
+        ):
+            return False
+        if not any(a == c for a, _, c in sliding_window(input, 3)):
+            return False
+        return True
+
+    return sum(map(is_nice, input.splitlines()))
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()