Maximum Subarray Sum Task

Given an array or list ARR consisting of N integers, your objective is to compute the maximum possible sum obtainable from a non-empty subarray (a contiguous sequence) within this array.

Example:

Input:

N = 5
ARR = [-2, 1, -3, 4, -1]

Output:

4

Explanation:

For the array [-2, 1, -3, 4, -1], the subarray [4] gives the maximum sum of 4.

Constraints:

• 1 ≤ N ≤ 5 * 105
• -109 ≤ ARR[i] ≤ 109
• Time Limit: 1 second