Need help to code this program using divide and conquer approche. Please add comments on the code. Also analyze complexity. I will rate you.

Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum. Example Input: [-2,1,-3,4,-1,2,1,-5,4], Output: 6 Explanation: [4,-1,2,1] has the largest sum - 6