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

解题报告：kadane算法，复杂度O（n）。

class Solution {
public:
    int maxSubArray(int A[], int n) {
        int max_so_far = A[0];
        int max_ending_here = 0;
        for(int i = 0; i != n; i++) {
          max_ending_here = max_ending_here + A[i];
            if(max_so_far < max_ending_here)
              max_so_far = max_ending_here;
            if(max_ending_here < 0)
               max_ending_here = 0;
        }
    return max_so_far;
    }
};