Islamic Universtiy,Bangladesh TopH 9th CPU CSE Programming Contest H. GCD Solution

 Problem Link :  https://toph.co/arena?contest=maadpgu#!/p/6474e358d47a320767bfdff1

Solution in C++:

1. /// Author : AH_Tonmoy
2. #include <bits/stdc++.h>
3. using namespace std;
4. int32_t main() {
5. ios_base::sync_with_stdio(0);
6. cin.tie(0);
7. int n;
8. cin >> n;
9. int a[n + 2], pre[n + 2], sup[n + 2];
10. cin >> a[1];
11. pre[1] = a[1];
12. for (int i = 2; i <= n; i++) {
13. cin >> a[i];
14. pre[i] = __gcd(pre[i - 1], a[i]);
15. }
16. sup[n] = a[n];
17. for (int i = n - 1; i >= 1; i--) {
18. sup[i] = __gcd(sup[i + 1], a[i]);
19. }
20. int q;
21. cin >> q;
22. while (q--) {
23. int l, r;
24. cin >> l >> r;
25. if (l - 1 == 0 && r + 1 <= n) {
26. cout << sup[r + 1] << '\n';
27. } else if (r + 1 > n && l - 1 >= 1) {
28. cout << pre[l - 1] << '\n';
29. } else if (r + 1 > n && l - 1 == 0) {
30. cout << "0" << endl;
31. } else
32. cout << __gcd(pre[l - 1], sup[r + 1]) << '\n';
33. }
34. }