Given an integer array nums, find the subarray with the largest sum, and return *its sum*.
The test cases are generated so that the answer will fit in a 32-bit integer.
Examples
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.