代码

#include <iostream>
#include <cstring>

using namespace std;
int n;
const int N = 207003;
int h[N],e[N],ne[N],idx;

bool find(int x){
    int t = (x%N+N)%N;
    //~i等价于i!=-1
    for(int i = h[t];~i;i=ne[i])if(e[i]==x)return true;
    return false;
}

//拉链法
void insert(int x){
    if(find(x))return;
    int t = (x%N+N)%N;
    e[idx] = x,ne[idx] = h[t],h[t] = idx++;
}


int main(){
    memset(h,-1,sizeof(h));
    int n,num;
    char cm[2];
    cin>>n;
    for(int i=0;i<n;i++){
        scanf("%s%d",cm,&num);
        if(*cm=='Q'){
            if(find(num))printf("Yes\n");
            else printf("No\n");
        }else insert(num);
    }
}