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;

    }

};