TheAlgorithms/Python · error · ValueError

Invalid Input

Error message

Invalid Input

What it means

Raised by max_sum_in_array() in maths/max_sum_sliding_window.py when len(array) < k or k < 0. The sliding-window algorithm needs at least one full window of size k inside the array, so a window larger than the array (or a negative size) makes the problem undefined and the function raises ValueError('Invalid Input').

Source

Thrown at maths/max_sum_sliding_window.py:31

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)}"
    )

View on GitHub (pinned to f5988cc097)

Solutions

1. Choose k <= len(array), typically k in [1, len(array)].
2. Clamp derived window sizes: k = max(1, min(k, len(array))).
3. Validate k against array length at the point where k is configured, not deep in the call stack.

Example fix

# before
max_sum_in_array([2, 1, 5, 1, 3, 2], 10)  # window larger than array

# after
k = min(10, len(arr))
max_sum_in_array(arr, k)

if not 1 <= k <= len(array):
    k = max(1, min(k, len(array)))  # or raise with your own message

When it happens

Trigger: max_sum_in_array(arr, 10) where arr has 9 or fewer elements (e.g. the doctest case arr=[2,1,5,1,3,2], k=10), or any negative k such as max_sum_in_array(arr, -1).

Common situations: k computed from user input or from len(array) arithmetic (e.g. k = len(arr) + margin), small test fixtures with a hardcoded window size, or off-by-one errors when deriving k.

Related errors

• surface_area_cube() only accepts non-negative values
• surface_area_cuboid() only accepts non-negative values
• surface_area_sphere() only accepts non-negative values
• surface_area_hemisphere() only accepts non-negative values
• surface_area_cone() only accepts non-negative values

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/0c6925fc55205e7c. Report an issue: GitHub.