LeetCode_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.

　　DP : B[i]为以A[i]节点作为截止节点的subarray的the largest sum，那么B[i] = max (A[i], B[i-1] + A[i]) ;

class Solution {
public:
    int maxSubArray(int A[], int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        vector<int> B(n,0);
        B[0] = A[0];
        int max = B[0];
        for(int i = 1; i< n; i++)
         {
              B[i] = B[i-1] + A[i] > A[i] ? B[i-1] + A[i] : A[i] ;
             max = max > B[i] ? max : B[i] ;
         }
         
         return max ;
    }
}；

 重写后：

class Solution {
public:
    int maxSubArray(int A[], int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int max = A[0];
        int test = A[0];
        for(int i = 1; i< n; ++i)
        {
            test = test + A[i] > A[i] ? test + A[i] : A[i];
            max = max > test ? max : test;
        }
        return max;
    }
};