https://leetcode.cn/problems/maximum-subarray/description/?envType=study-plan-v2&envId=top-100-liked

class Solution {
    
    
public:
    int maxSubArray(vector<int>& nums) {
    
    
        int pre = 0, ret = nums[0];
        for (auto& e : nums) {
    
    
            pre = max(pre + e, e);
            ret = max(ret, pre);
        }
        return ret;
    }
};