Problem p02269 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <cstdlib>
#include <iostream>
#include <queue>
#include <stack>
#include <string>
#include <vector>
typedef long long ll;
using namespace std;
#define M 1020751

long long convert(string word);
void insert(long long *d, long long key);
int find_key(long long *d, long long key);
int h1(long long key);
int h2(long long key);
int main() {
  int i, n;
  cin >> n;
  string order, word;
  long long key;
  long long d[M];
  queue<string> q;
  for (i = 0; i < M; i++) {
    d[i] = -1;
  }
  for (i = 0; i < n; i++) {
    cin >> order >> word;
    key = convert(word);
    if (order[0] == 'i') {
      insert(d, key);
    } else {
      int flag = find_key(d, key);
      if (flag == 1) {
        q.push("yes");
      } else {
        q.push("no");
      }
    }
  }
  while (!q.empty()) {
    cout << q.front() << endl;
    q.pop();
  }
}

long long convert(string word) {
  long long i, num = 0, keta = 1;
  for (i = 0; i < word.size(); i++) {
    if (word[i] == 'A') {
      num += keta;
    } else if (word[i] == 'C') {
      num += keta * 2;
    } else if (word[i] == 'G') {
      num += keta * 3;
    } else {
      num += keta * 4;
    }
    keta *= 10;
  }
  return num;
}
void insert(long long *d, long long key) {
  int h, i = 1;
  h = h1(key);
  while (d[h] != -1) {
    h = (h1(key) + i * h2(key)) % M;
    i++;
  }
  d[h] = key;
}
int find_key(long long *d, long long key) {
  int h, i = 0;
  h = h1(key);
  while (1) {
    if (d[h] == -1) {
      return 0;
    } else if (d[h] != key) {
      i++;
      h = (h1(key) + h2(key)) % M;
    } else {
      return 1;
    }
  }
}
int h1(long long key) { return key % M; }
int h2(long long key) { return 1 + (key % (M - 1)); }

Fixed submission:
#include <algorithm>
#include <cstdlib>
#include <iostream>
#include <queue>
#include <stack>
#include <string>
#include <vector>
typedef long long ll;
using namespace std;
#define M 1020751

long long convert(string word);
void insert(long long *d, long long key);
int find_key(long long *d, long long key);
int h1(long long key);
int h2(long long key);
int main() {
  int i, n;
  cin >> n;
  string order, word;
  long long key;
  long long d[M];
  queue<string> q;
  for (i = 0; i < M; i++) {
    d[i] = -1;
  }
  for (i = 0; i < n; i++) {
    cin >> order >> word;
    key = convert(word);
    if (order[0] == 'i') {
      insert(d, key);
    } else {
      int flag = find_key(d, key);
      if (flag == 1) {
        q.push("yes");
      } else {
        q.push("no");
      }
    }
  }
  while (!q.empty()) {
    cout << q.front() << endl;
    q.pop();
  }
}

long long convert(string word) {
  long long i, num = 0, keta = 1;
  for (i = 0; i < word.size(); i++) {
    if (word[i] == 'A') {
      num += keta;
    } else if (word[i] == 'C') {
      num += keta * 2;
    } else if (word[i] == 'G') {
      num += keta * 3;
    } else {
      num += keta * 4;
    }
    keta *= 10;
  }
  return num;
}
void insert(long long *d, long long key) {
  int h, i = 1;
  h = h1(key);
  while (d[h] != -1) {
    h = (h1(key) + i * h2(key)) % M;
    i++;
  }
  d[h] = key;
}
int find_key(long long *d, long long key) {
  int h, i = 0;
  h = h1(key);
  while (1) {
    if (d[h] == -1) {
      return 0;
    } else if (d[h] != key) {
      i++;
      h = (h1(key) + i * h2(key)) % M;
    } else {
      return 1;
    }
  }
}
int h1(long long key) { return key % M; }
int h2(long long key) { return 1 + (key % (M - 1)); }