Given an integer array nums, find the subarray with the largest sum, and return its sum.
- An array of integers
nums.
- 1 <= nums.length <= 10^5
- -10^4 <= nums[i] <= 10^4
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.