#include <vector> class Solution { public: //利用归并排序 long long ans; vector<int> a; vector<int>t; void merge(int l,int r,int mid){ int i=l,j=mid,p=l; cout<<l<<r<<" "; while(i<mid&&j<=r){ if(a[i]<=a[j]) t[p++]=a[i++]; else { t[p++]=a[j++]; ans+=(mid-i);//只在归...