diegomzalez/arr_item_sum

Optimized Python function using recursion to sum list elements. Employs divide-and-conquer and avoids list slicing. Includes tests, README, and MIT license. Note: not suitable for very large lists due to recursion depth limit.

Array Item Sum - Recursive Implementation

This project presents an optimized Python function that calculates the sum of all elements in a list using recursion. This approach demonstrates the concept of recursion in Python with a divide-and-conquer strategy. Due to Python's recursion limit, caution should be used when dealing with large lists.

Function

Here's the core function of the project:

def arr_item_sum(arr: list, left: int = 0, right: int = None) -> int:
    if not right:
        right = len(arr)

    if left >= right:
        return 0
    elif (right - left) == 1:
        return arr[left]
    elif (right - left) == 2:
        return arr[left] + arr[left+1]
    else:
        mid = (left + right) // 2
        return arr_item_sum(arr, left, mid) + arr[mid] + arr_item_sum(arr, mid+1, right)

Usage

To use the function, simply call it with a list of numbers as the argument:

numbers = [1, 2, 3, 4, 5]
print(arr_item_sum(numbers))  # Outputs: 15

Limitations

This implementation uses recursion, and Python has a limit to the recursion depth (typically 1000). Therefore, this function may result in a RecursionError for larger lists.

For list lengths close to or exceeding this limit, it's recommended to use an iterative approach or Python libraries optimized for large computations, like numpy.

Contributing

Feel free to fork this project and add your own features or improvements.