2021: d01: ex2: add solution

2021/d01/ex2/ex2.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python
+
+import collections
+import itertools
+import sys
+from typing import List
+
+
+def sliding_window(iterable, n):
+    it = iter(iterable)
+    window = collections.deque(itertools.islice(it, n), maxlen=n)
+    if len(window) == n:
+        yield tuple(window)
+    for x in it:
+        window.append(x)
+        yield tuple(window)
+
+
+def solve(input: List[int]) -> int:
+    windowed = [sum(window) for window in sliding_window(input, 3)]
+    return sum(prev < cur for (prev, cur) in itertools.pairwise(windowed))
+
+
+def main() -> None:
+    input = [int(line) for line in sys.stdin.readlines()]
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()