Created max_sum_sliding_window in Python/other (#3065)

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* Update max_sum_sliding_window.py

* Update max_sum_sliding_window.py

* Update max_sum_sliding_window.py

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* Update max_sum_sliding_window.py

* Update max_sum_sliding_window.py

other/max_sum_sliding_window.py

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+"""
+Given an array of integer elements and an integer 'k', we are required to find the
+maximum sum of 'k' consecutive elements in the array.
+
+Instead of using a nested for loop, in a Brute force approach we will use a technique
+called 'Window sliding technique' where the nested loops can be converted to a single
+loop to reduce time complexity.
+"""
+from typing import List
+
+
+def max_sum_in_array(array: List[int], k: int) -> int:
+    """
+    Returns the maximum sum of k consecutive elements
+    >>> arr = [1, 4, 2, 10, 2, 3, 1, 0, 20]
+    >>> k = 4
+    >>> max_sum_in_array(arr, k)
+    24
+    >>> k = 10
+    >>> max_sum_in_array(arr,k)
+    Traceback (most recent call last):
+        ...
+    ValueError: Invalid Input
+    >>> arr = [1, 4, 2, 10, 2, 13, 1, 0, 2]
+    >>> k = 4
+    >>> max_sum_in_array(arr, k)
+    27
+    """
+    if len(array) < k or k < 0:
+        raise ValueError("Invalid Input")
+    max_sum = current_sum = sum(array[:k])
+    for i in range(len(array) - k):
+        current_sum = current_sum - array[i] + array[i + k]
+        max_sum = max(max_sum, current_sum)
+    return max_sum
+
+
+if __name__ == "__main__":
+    from doctest import testmod
+    from random import randint
+
+    testmod()
+    array = [randint(-1000, 1000) for i in range(100)]
+    k = randint(0, 110)
+    print(f"The maximum sum of {k} consecutive elements is {max_sum_in_array(array,k)}")