int maxSubArray(vector<int> &nums)

Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.

Example 1:

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

Example 2:

Input: nums = [1]
Output: 1

Example 3:

Input: nums = [0]
Output: 0

Example 4:

Input: nums = [-1]
Output: -1

Example 5:

Input: nums = [-100000]
Output: -100000

Constraints:

• 1 <= nums.length <= 3 * 10⁴
• -10⁵ <= nums[i] <= 10⁵

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.