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.

click to show more practice.

More practice:

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

more practice是搞笑的。

还有更简单的方法，懒得改了。事实证明看书太多也不好。

class Solution {
public:
    int maxSubArray(int A[], int n) {
        vector<int> sum;
        if(n == 0)return 0;
        int maxsum =A[0];
        sum.push_back(A[0]);
        for(int i = 1 ; i < n ; i++)
        {
            int temp = sum[i-1]+A[i];
            if(temp > maxsum)maxsum = temp;
            sum.push_back(temp);
        }

        int min = 0;
        for(int i = 1 ; i < n;i++)
        {
            if(sum[i] - sum[min] > maxsum)
            maxsum = sum[i] - sum[min];
            if(sum[i] < sum[min])min = i;
        }
        
        
        return maxsum;
    }
};