fixed size sliding window technique

Author: asRot0

data_structures/sliding_window/fixed_size_window.py

@@ -0,0 +1,59 @@
+"""
+Fixed-Size Sliding Window Algorithm
+
+This module contains an implementation of the fixed-size
+sliding window algorithm with doctests.
+
+Examples:
+    >>> max_sum_subarray([1, 2, 3, 4, 5], 3)
+    12
+
+    >>> max_sum_subarray([2, 1, 5, 1, 3, 2], 4)
+    11
+"""
+
+
+def max_sum_subarray(arr: list[int], k: int) -> int:
+    """
+    Find the maximum sum of any subarray of size `k`.
+
+    Args:
+        arr: The input array of integers.
+        k: The size of the subarray.
+
+    Returns:
+        The maximum sum of a subarray of size `k`.
+
+    Raises:
+        ValueError: If the length of the array is less than `k`.
+
+    Examples:
+        >>> max_sum_subarray([1, 2, 3, 4, 5], 3)
+        12
+
+        >>> max_sum_subarray([2, 1, 5, 1, 3, 2], 4)
+        11
+
+        >>> max_sum_subarray([1, 2], 3)
+        Traceback (most recent call last):
+            ...
+        ValueError: Array length must be at least as large as the window size.
+    """
+    if len(arr) < k:
+        raise ValueError("Array length must be at least as large as the window size.")
+
+    max_sum = float('-inf')
+    window_sum = sum(arr[:k])
+    max_sum = max(max_sum, window_sum)
+
+    for i in range(len(arr) - k):
+        window_sum = window_sum - arr[i] + arr[i + k]
+        max_sum = max(max_sum, window_sum)
+
+    return max_sum
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()