借鉴了左程云大神算法课里面求小和的思路 public: long long merge(vector<int>& nums,int L,int M,int R ){ vector<int>help(R-L+1); int sum = 0; int i = 0; int p1 = L; int p2 = M+1; while(p1<=M&&p2<=R){ sum += nums[p1]>nums[p2]?(M-p1+1):0; help[i++] = nums[p1]<nums[p2]?nums[p1++]:nums[p2+...