Given an integer array nums, find the subarray with the largest sum, and return its sum.

  Example 1:

Input: nums = [-2,1,-3,4,-1,2,1,-5,4] Output: 6 Explanation: The subarray [4,-1,2,1] has the largest sum 6.

Example 2:

Input: nums = [1] Output: 1 Explanation: The subarray [1] has the largest sum 1.

Example 3:

Input: nums = [5,4,-1,7,8] Output: 23 Explanation: The subarray [5,4,-1,7,8] has the largest sum 23.

  Constraints:

1 <= nums.length <= 10⁵
-10⁴ <= nums[i] <= 10⁴

  Follow up: If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle.