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  1. #include <iostream>
  2. #include <cmath>
  3. using namespace std;
  4.  
  5. bool is_prime(int m){
  6. 	if (m < 2) return false;
  7. 	if (m == 2) return true;
  8. 	if (m % 2 == 0) return false;
  9. 	int limit = sqrt(m);
  10. 	for (int i = 3; i <= limit; i += 2){
  11. 		if (m % i == 0) return false;
  12. 	}
  13. 	return true;
  14. }
  15.  
  16.  
  17. int prime_count(int k){
  18. 	int p_c = 0;
  19. 	for (int i = 2; i <= k; i++){
  20. 		p_c = p_c + is_prime(i);
  21. 	}
  22. 	return p_c;
  23. }
  24.  
  25. int main() {
  26. 	int n;
  27. 	cin >> n;
  28. 	int t [2*n];
  29. 	for (int i = 0; i < n * 2; i++){
  30. 		cin >> t[i];
  31. 	}
  32. 	for (int j = 0; j < 2 * n; j += 2){
  33. 	int a = t[j];
  34. 	int b = t[j + 1];
  35. 	int k = prime_count(b) - prime_count(a - 1);
  36. 	cout << k << endl;
  37. }
  38. 	return 0;
  39. }
Success #stdin #stdout 0s 5316KB
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https://ideone.com/ud6DgU
language:
C++ (gcc 8.3)
created:
1 day ago
visibility:
public

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