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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define SIZE 123456
  4.  
  5. int main(void) {
  6. 	int i = 0, j = 0,count = 0;
  7. 	int prime[SIZE];
  8. 	int my_prime[SIZE];
  9. 	for(i=1; i < SIZE; ++i)
  10. 		prime[i] = i;
  11. 	for(i = 2; i < SIZE; ++i) {
  12. 		if(prime[i]) {
  13. 			my_prime[count++] = prime[i];
  14. 			j = i + i;
  15. 			for(; j < SIZE; j += i){
  16. 				prime[j] = 0;
  17. 			}
  18. 		}
  19. 	}
  20.  
  21. 	int T = 0;
  22. 	scanf("%d",&T);
  23. 	while(T--) {
  24. 		int a = 0, b = 0;
  25. 		scanf("%d %d",&a,&b);
  26. 		int test = a - b;
  27. 		unsigned long long int num = 1;
  28. 		while(test--) {
  29. 			num = num * a--;
  30. 		}
  31. 		int res = 0;
  32. 		for(i = 0;i < count ;++i) {
  33. 			while(num % my_prime[i] == 0) {
  34. 				num /= my_prime[i];
  35. 			}
  36. 			++res;
  37. 			if(num == 1)
  38. 				break;
  39. 		}
  40. 		printf("%d\n",res);
  41.  
  42. 	}
  43.  
  44. 	return 0;
  45. }
  46.  
Success #stdin #stdout 0s 3992KB
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https://ideone.com/2eGhhs
language:
C++ (gcc 8.3)
created:
8 years ago
visibility:
secret

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