Language: C++

#include<iostream>
#include<cstdlib>
using namespace std;

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

char H[M][L];

// ???????????°????????????
int getChar(char ch) {
	switch (ch) {
	case 'A' : return 1;
	case 'C' : return 2;
	case 'G' : return 3;
	case 'T' : return 4;
	default  : return 0;
	}
}

// ?????????????????°??????????????????key?????????
// ???????????\??¢??°
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++) {
		// ???????????\?????????????????´??????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, 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;
		}
	}
	return 0;
}


int main() {
	int n;
	char com[6], str[L];

	for (int i = 0; i < M; i++) H[i][0] = '\0';

	cin >> n;
	for (int i = 0; i < n; i++) {
		scanf("%s %s", com, str);
		if (com[0] == 'i') insert(str);
		else if (com[0] == 'f') {
			if (find(str)) printf("yes\n");
			else printf("no\n");
		}
	}
}

Compiler output:
a.cc: In function 'long long int getkey(char*)':
a.cc:26:25: error: 'strlen' was not declared in this scope
   26 |         for (i = 0; i < strlen(str); i++) {
      |                         ^~~~~~
a.cc:3:1: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    2 | #include<cstdlib>
  +++ |+#include <cstring>
    3 | using namespace std;
a.cc: In function 'int find(char*)':
a.cc:43:21: error: 'strcmp' was not declared in this scope
   43 |                 if (strcmp(H[h], str) == 0) return 1;
      |                     ^~~~~~
a.cc:43:21: note: 'strcmp' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc:45:26: error: 'strlen' was not declared in this scope
   45 |                 else if (strlen(H[h]) == 0) return 0;
      |                          ^~~~~~
a.cc:45:26: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc: In function 'int insert(char*)':
a.cc:55:21: error: 'strcmp' was not declared in this scope
   55 |                 if (strcmp(H[h], str) == 0) return 1;
      |                     ^~~~~~
a.cc:55:21: note: 'strcmp' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc:56:26: error: 'strlen' was not declared in this scope
   56 |                 else if (strlen(H[h]) == 0) {
      |                          ^~~~~~
a.cc:56:26: note: 'strlen' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
a.cc:57:25: error: 'strcpy' was not declared in this scope
   57 |                         strcpy(H[h], str);
      |                         ^~~~~~
a.cc:57:25: note: 'strcpy' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'