又偷懒了…直接用stl的map

#include<bits/stdc++.h>
using namespace std;
map<long long,bool>mp1;
int main(){
    int n;
    cin>>n;
    for(int i=1;i<=n;i++){
        char operat;
        long long x;
        cin>>operat>>x;
        if(operat=='I')mp1[x]=1;
        else {
            if(mp1[x])cout<<"Yes"<<endl;
            else cout<<"No"<<endl;
        }

    }
}