1895队列操作C++

参考代码:

#include<bits/stdc++.h>

using namespace std;

int main()

{

             int n,x,op;

             cin>>n;

             queue<int> q;

             while(n--)

             {

                         cin>>op;

                         if(op==1)

                         {

                                 cin>>x;

                                 q.push(x);

                         }

                         else if(op==2)

                         {

                                 if(!q.empty())

                                 {

                                          cout<<q.front()<<endl;

                                         q.pop();

                                 }

                                 else

                                 {

                                         cout<<"no";

                                         break;

                                 }

                         }

                         else if(op==3)

                         {

                                  cout<<q.size()<<endl;

                         }

             }

             return 0;

}