Maximum Subarray

Find the contiguous subarray within an array (containing at least one number) which has the largest sum.

For example, given the array [−2,1,−3,4,−1,2,1,−5,4],
the contiguous subarray [4,−1,2,1] has the largest sum = 6.

题意：

利用动态规划的思想完成，时间复杂度为O(n)。已知0,..,k的最大和以后，0,...k+1的最大和为：

1）若sum[k]>=0,sum[k+1]=sum[k]+A[k+1]。

2）若sum[k]<0,sum[k+1]=A[k+1]。

class Solution {public:  int maxSubArray(int A[], int n){    int max_fi = INT_MIN;    int fi = 0;    for(int i = 0; i < n; i++){      //fi = max(fi + A[i], fi);  ->出错, fi表示的是以i为结尾的子最大子数组（即A[i]元素一定要加入），如果前面部分对总和起到加的作用，就加入，否则就不加      fi = max(fi + A[i], A[i]);      max_fi = max(max_fi, fi);    }    return max_fi;  }};