拉链法（数组+链表）

#include<iostream>
#include<cstring>

using namespace std;

const int N = 100003;

int h[N], e[N], ne[N], idx;


void insert(int x){
    int k = ((x % N) + N) % N;  //哈希值

    e[idx] = x, ne[idx] = h[k], h[k] = idx++;
}

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

int main(){
    int n;
    scanf("%d", &n);

    memset(h, -1, sizeof h);
    while(n--){
        char op[2];
        int x;
        scanf("%s%d", op, &x);

        if(*op == 'I') insert(x);
        else{
            if(find(x)) puts("Yes");
            else puts("No");
        }
    }
    return 0;
}

开放寻址法

#include<iostream>
#include<cstring>

using namespace std;

const int N = 200003, null = 0x3f3f3f3f;

int h[N];

int find(int x){
    int k = ((x % N) + N) % N;  //哈希值
    while(h[k] != null && h[k] != x){
        k++;
        if(k == N) k = 0;
    }
    return k;
}

int main(){
    int n;
    scanf("%d", &n);

    memset(h, null, sizeof h);
    while(n--){
        char op[2];
        int x;
        scanf("%s%d", op, &x);

        if(*op == 'I'){
            int k = find(x);
            h[k] = x;
        }
        else{
            int k = find(x);
            if(h[k] == x) puts("Yes");
            else puts("No");
        }
    }
    return 0;
}