C++ vector中使用pair

vector<pair<int,int> > 

#include<bits/stdc++.h>
using namespace std;
int main()
{
    vector<pair<int, int>> vec;
    vec.emplace_back(make_pair(1,2));
    cout<<vec[0].first<<" "<<vec[0].second<<endl;
    cout<<vec.size()<<endl;
    vec.pop_back();
    cout<<vec.size()<<endl;
   return 0;
}

reference：

https://blog.csdn.net/linxihe123/article/details/70173476