LeetCode 53. 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.

区间最大和问题，只需要用一个变量维护上一个区间的和，如果小于0的话就舍弃，大于0的话就加上。

class Solution {
public:
    int maxSubArray(vector<int>& nums) {
        int ans = INT_MIN, res = 0;
        for(size_t i = 0; i < nums.size(); ++ i)
        {
            if(res < 0)
                res = 0;
            res += nums[i];
            ans = max(ans, res);
        }
        return ans;
    }
};