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  1. #include<stdio.h>
  2. #define range 5000000000000000001
  3. unsigned long long int trailing_zeros(int n)
  4. {
  5. 	unsigned long long int p=n,sum1=0,sum2=0;
  6. 	while(p!=0)
  7. 	{
  8. 		sum1+=p/2;
  9. 		p=p/2;
  10. 	}
  11. 	p=n;
  12. 	while(p!=0)
  13. 	{
  14. 		sum2+=p/5;
  15. 		p=p/5;
  16. 	}
  17. 	if(sum1<sum2)
  18. 		return sum1;
  19. 	else return sum2;
  20. }
  21. unsigned long long int bi_search(unsigned long long int low,unsigned long long int high,unsigned long long int zeros)
  22. {
  23. 	unsigned long long int mid;
  24. 	while(low<=high)
  25. 	{
  26. 		mid=(low+high)/2;
  27. 		if(trailing_zeros(mid)==zeros)
  28. 			break;
  29. 		if(zeros<trailing_zeros(mid))
  30. 			high=mid-1;
  31. 		else
  32. 			low=mid+1;
  33. 	}
  34. 	if(low>high)
  35. 		return 0;
  36. 	else return mid;
  37. }
  38. int main()
  39. {
  40. 	unsigned long long z,n;
  41. 	int r=0,t;
  42. 	scanf("%d",&t);
  43. 	while(t--)
  44. 	{
  45. 		scanf("%llu",&n);
  46. 		z=bi_search(1,range,n);
  47. 		if(z==0)
  48. 			printf("Case %d: impossible\n",++r);
  49. 			else{
  50. 		while(trailing_zeros(z-1)==n)
  51. 		{
  52. 			z=bi_search(1,z-1,n);
  53. 		}
  54. 		printf("Case %d: %llu\n",++r,z);
  55. 			}
  56. 	}
  57. 	return 0;
  58. }
Success #stdin #stdout 0s 3344KB
comments (?)
stdin
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4
1
2
5
1000000000000000000
stdout
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Case 1: 5
Case 2: 10
Case 3: impossible
Case 4: impossible
https://ideone.com/dji0pk
language:
C++ (gcc 8.3)
created:
10 years ago
visibility:
public

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