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  1. #include <iostream>
  2. #include <math.h>
  3. using namespace std;
  4.  
  5. int main() {
  6. 	long long collatz(long long),n,test,k,count=0;
  7. 	for(n=pow(10,7)/2;n<pow(10,7);n++)
  8. 		{
  9. 			k=1;
  10. 			test=n;
  11. 			while(collatz(test)!=1)
  12. 				{
  13. 					test=collatz(test);
  14. 					k++;
  15. 				}
  16. 			if(k%2==1)
  17. 				count++;
  18. 		}
  19. 	cout<<count;
  20. 	return 0;
  21. }
  22. long long collatz(long long x)
  23. 	{
  24. 		return (x%2==0) ? x/2 : 3*x+1;
  25. 	}
Success #stdin #stdout 13.8s 3460KB
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2509387
https://ideone.com/v1urOz
(2nd run) https://b...content-available-to-author-only...t.org/problems/collatz-conjecture-an-odd-number-of-steps/
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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