Language: C++

#include<cstdio>
#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
using namespace std;
#define M 1046527
#define NIL (-1)
#define L 14

char H[M][L];

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;
	for (int 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, h;
	key = getKey(str);
	for (int 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;
	}
	return 0;
}

int insert(char str[]) {
	long long key, h;
	key = getKey(str);
	for (int 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_s(H[h], str);
			return 0;
		}
	}
	return 0;
}

int main(void) {
	int n, h;
	char str[L], com[9];
	
	//for (int i = 0; i < M; i++) H[i][0] = '\0';
	scanf_s("%d ", &n);
	for (int i = 0; i < n; i++) {
		cin >> com >> str;
		printf("%s %s\n", 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:23:29: error: 'strlen' was not declared in this scope
   23 |         for (int i = 0; i < strlen(str); i++) {
      |                             ^~~~~~
a.cc:6:1: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    5 | #include<algorithm>
  +++ |+#include <cstring>
    6 | using namespace std;
a.cc: In function 'int find(char*)':
a.cc:38:21: error: 'strcmp' was not declared in this scope
   38 |                 if (strcmp(H[h], str) == 0)return 1;
      |                     ^~~~~~
a.cc:38:21: note: 'strcmp' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc:39:26: error: 'strlen' was not declared in this scope
   39 |                 else if (strlen(H[h]) == 0)return 0;
      |                          ^~~~~~
a.cc:39:26: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc: In function 'int insert(char*)':
a.cc:49:21: error: 'strcmp' was not declared in this scope
   49 |                 if (strcmp(H[h], str) == 0)return 1;
      |                     ^~~~~~
a.cc:49:21: note: 'strcmp' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc:50:26: error: 'strlen' was not declared in this scope
   50 |                 else if (strlen(H[h]) == 0) {
      |                          ^~~~~~
a.cc:50:26: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc:51:25: error: 'strcpy_s' was not declared in this scope
   51 |                         strcpy_s(H[h], str);
      |                         ^~~~~~~~
a.cc: In function 'int main()':
a.cc:63:9: error: 'scanf_s' was not declared in this scope; did you mean 'scanf'?
   63 |         scanf_s("%d ", &n);
      |         ^~~~~~~
      |         scanf