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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. const int M = 31630;
  5. bool f[M + 1];
  6. int n, m, k;
  7. vector<int> prime;
  8. void siv() {
  9. 	f[0] = f[1] = 1;
  10. 	for (int i = 4; i <= M; i += 2)
  11. 		f[i] = 1;
  12. 	for (int i = 3; i * i <= M; i += 2)
  13. 		if (!f[i])
  14. 			for (int j = i * i; j <= M; j += i)
  15. 				f[j] = 1;
  16. 	prime.push_back(2);
  17. 	for (int i = 3; i <= M; i += 2)
  18. 		if (!f[i])
  19. 			prime.push_back(i);
  20.  
  21. }
  22. int fact(int x, int k) {
  23. 	int p = 1, sum;
  24. 	for (int i = 0, ln = prime.size(); i < ln && prime[i] * prime[i] <= x;
  25. 			++i) {
  26. 		for (sum = 1; x % prime[i] == 0; ++sum, x /= prime[i])
  27. 			;
  28. 		p *= sum;
  29. 		if (p > k)
  30. 			return 0;
  31. 	}
  32. 	if (x > 1)
  33. 		p *= 2;
  34. 	return p == k;
  35. }
  36. int main() {
  37. 	//freopen("a.in", "r", stdin);
  38. 	siv();
  39. 	int ans;
  40. 	while (scanf("%d%d%d", &n, &m, &k) == 3) {
  41. 		for (ans = 0; n <= m; ans += fact(n++, k))
  42. 			;
  43. 		printf("%d\n", ans);
  44. 	}
  45. }
  46.  
  47.  
Success #stdin #stdout 0s 3456KB
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https://ideone.com/fL6YdT
language:
C++ (gcc 8.3)
created:
9 years ago
visibility:
public

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