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  1. #include <bits/stdc++.h>
  2.  
  3. #define INF 100000000
  4. #define MOD 1000000007
  5. #define MAXN 100005
  6. #define ins insert
  7. #define pb push_back
  8. #define mp make_pair
  9. #define sz size
  10. #define sd(n) scanf("%d",&n)
  11. #define pdn(n) printf("%d\n",n)
  12. #define pd(n) printf("%d ",n)
  13. #define nl() printf("\n")
  14. using namespace std;
  15.  
  16. typedef long long ll;
  17. typedef unsigned long long ull;
  18. typedef vector<int> vi;
  19. typedef vector<vi> vii;
  20. typedef pair<int, int> pii;
  21.  
  22. vi primes;
  23.  
  24. bool check[MAXN];
  25.  
  26. int main() {
  27. 	//clock_t start=clock(); //Sieve
  28. 	for (int i = 2; i <= 31623; ++i) {
  29. 		if (!check[i]) {
  30. 			primes.pb(i);
  31. 			for (int j = i+i; j <= 31623; j += i)
  32. 				check[j] = true;
  33. 		}
  34. 	}
  35.  
  36. 	int lim = primes.sz();
  37. 	int a, b, n; sd(a), sd(b), sd(n);
  38. 	int countt = 0; //final answer
  39. 	for (int i = a; i <= b; ++i) {
  40. 		int x = 1; //Count of divisors of i 
  41. 		int temp = i;
  42. 		/*vi::iterator it = lower_bound(primes.begin(), primes.end(), temp); //If the number is prime we know it has 2 divisors.
  43. 		if (*it == temp) { 													 //This makes it slower so I have commented this part.					
  44. 			x *= 2;
  45. 			if (x == n)
  46. 				++countt;
  47. 			continue;
  48. 		}*/
  49. 		for (int j = 0; (primes[j]*primes[j] <= i) && (j < lim); ++j) { 
  50. 			if (!(temp % primes[j])) {
  51. 				int cc = 0;	
  52. 				while (!(temp % primes[j])) {
  53. 					temp /= primes[j];
  54. 					cc++;
  55. 				}
  56. 				x *= (cc+1);
  57. 				if (x > n)
  58. 					break;
  59. 			}
  60. 		}
  61. 		if (temp != 1)
  62. 				x *= 2;
  63. 		if (x == n)
  64. 			++countt;	
  65. 	}	
  66. 	pdn(countt);
  67. 	//clock_t stop=clock();
  68. 	//double elapsed=(double)(stop-start) * 1000.0 / CLOCKS_PER_SEC;
  69. 	//printf("Time elapsed in ms : %f",elapsed);
  70.     return 0;
  71. }
Success #stdin #stdout 0s 3528KB
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https://ideone.com/KjCN97
language:
C++ (gcc 8.3)
created:
10 years ago
visibility:
public

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