开放寻址法

#include<iostream>
#include<algorithm>
#include<cstring>
#include<string>
using namespace std;
const int N =200003,null=0x3f3f3f3f;
int a[N];
int find(int x) {
    int k = (x % N + N) % N;//重点哈希公式
    while (a[k] != null && a[k] != x) {
        k++;
        if (k == N) k = 0;
    }
    return k;
}


int main()
{
    memset(a, null, sizeof(a));
    int n; cin >> n; int x; 
    while (n--) {
        string s; cin >> s;
        scanf("%d", &x);
        int k = find(x);
        if (s == "I") a[k] = x;
        else {
            if(a[k]==x)  printf("Yes\n");
            else printf("No\n");
        }
    }
    return 0;
}

字符串哈希

注意点！！！！

#include<iostream>
#include<string>
using namespace std;
typedef unsigned long long ULL;
const int N=100001;char str[N];
ULL a[N],p[N];int P=131;
ULL get(int l,int r){
    return a[r]-a[l-1]*p[r-l+1];
}
int main(){
    int n,m;cin>>n>>m;
    scanf("%s",str+1);
    p[0]=1;
    for(int i=1;i<=n;i++){
        a[i]=a[i-1]*P+str[i];//存放字符串哈希
        p[i]=p[i-1]*P;//存放p进制数
    }
    while(m--){
           int l1,r1,l2,r2;
           scanf("%d%d%d%d",&l1,&r1,&l2,&r2);
           if(get(l1,r1)==get(l2,r2)) puts("Yes");
           else puts("No");
    }
    return 0;
}