模拟队列

题目链接：https://www.acwing.com/problem/content/831/

数组模拟队列

#include <bits/stdc++.h>
using namespace std;
const int N=1e5+10;
int a[N];
int h=0,t=0,n;
int main()
{
    cin>>n;
    while(n--){
        string s;
        int x;
        cin>>s;
        if(s=="push"){
            cin>>x;
            a[++t]=x;
        }else if(s=="pop"){
            ++h;
        }else if(s=="empty"){
            if(h>=t){
                cout<<"YES"<<endl;
            }else{
                cout<<"NO"<<endl;
            }
        }else if(s=="query"){
            cout<<a[h+1]<<endl;
        }
    }
    return 0;
}