Language: C++

#include <iostream>
#include <cstdio>
#include <stack>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;

#define M 1046527
#define NIL (-1)
#define L 14

char H[M][L]; // hash table

int getChar(char ch){
    if (ch == 'A') return 1;
    else if (ch == 'C') return 2;
    else if (ch == 'G') return 3;
    else if (ch == 'T') return 4;
    else return 0;
}

long long getKey(char str[]){
    long long sum = 0, p = 1, i;
    for (i = 0; i < strlen(str); i++){
        sum += p * (getChar(str[i]));
        p *= 5;
    }
    return sum;
}

int h1(int key){return key % M;}
int h2(int key){return 1 + (key % (M - 1));}

int find(char str[]){
    long long key, i, h;
    key = getKey(str);
    for (i = 0;; i++){
        h = (h1(key) + i * h2(key)) % M;
        if (strcmp(H[h], str) == 0) return 1;
        else if (strlen(H[h]) == 0) return 0;
    }
}

int insert(char str[]){
    long long key, i, h;
    key = getKey(str);
    for (i = 0;; i++){
        h = (h1(key) + i * h2(key)) % M;
        if (strcmp(H[h], str) == 0) return 1;
        else if (strlen(H[h]) == 0) {
            strcpy(H[h], str);
            return 0;
        }
    }
}

int main() {
    int i, n, h;
    char str[L], com[9];
    for (i = 0; i < M; i++) H[i][0] = '\0';
    scanf("%d", &n);
    for (i = 0; i < n; i++){
        scanf("%s %s", com, str);

        if (com[0] == 'i'){
            insert(str);
        }
        else {
            if (find(str)){
                printf("yes\n");
            }
            else{
                printf("No\n");
            }
        }
    }

    return 0;

}

Compiler output:
a.cc: In function 'long long int getKey(char*)':
a.cc:25:21: error: 'strlen' was not declared in this scope
   25 |     for (i = 0; i < strlen(str); i++){
      |                     ^~~~~~
a.cc:7:1: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    6 | #include <algorithm>
  +++ |+#include <cstring>
    7 | using namespace std;
a.cc: In function 'int find(char*)':
a.cc:40:13: error: 'strcmp' was not declared in this scope
   40 |         if (strcmp(H[h], str) == 0) return 1;
      |             ^~~~~~
a.cc:40:13: note: 'strcmp' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc:41:18: error: 'strlen' was not declared in this scope
   41 |         else if (strlen(H[h]) == 0) return 0;
      |                  ^~~~~~
a.cc:41:18: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc: In function 'int insert(char*)':
a.cc:50:13: error: 'strcmp' was not declared in this scope
   50 |         if (strcmp(H[h], str) == 0) return 1;
      |             ^~~~~~
a.cc:50:13: note: 'strcmp' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc:51:18: error: 'strlen' was not declared in this scope
   51 |         else if (strlen(H[h]) == 0) {
      |                  ^~~~~~
a.cc:51:18: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc:52:13: error: 'strcpy' was not declared in this scope
   52 |             strcpy(H[h], str);
      |             ^~~~~~
a.cc:52:13: note: 'strcpy' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'