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  1. #include <algorithm>
  2. #include <iostream>
  3. #include <iterator>
  4.  
  5. struct triple_t
  6. {
  7. 	unsigned x;
  8. 	unsigned y;
  9. 	unsigned z;
  10. };
  11.  
  12. std::ostream & operator<<(std::ostream & out, triple_t const & triple)
  13. {
  14. 	return out << triple.x << ", " << triple.y << ", " << triple.z;
  15. }
  16.  
  17. class triple_iterator_t : public std::iterator<std::forward_iterator_tag, triple_t>
  18. {
  19. private:
  20. 	triple_t triple_{3, 4, 5};
  21.  
  22. 	static triple_t next(unsigned x, unsigned y, unsigned z)
  23. 	{
  24. 		while (true)
  25. 		{
  26. 			if (++y == z)
  27. 			{
  28. 				if (++x == y)
  29. 				{
  30. 					++z;
  31. 					x = 1;
  32. 				}
  33. 				y = x;
  34. 			}
  35.  
  36. 			if (x * x + y * y == z * z) return {x, y, z};
  37. 		}
  38. 	}
  39.  
  40. public:
  41. 	triple_t operator *()
  42. 	{
  43. 		return triple_;
  44. 	}
  45.  
  46. 	triple_iterator_t & operator ++()
  47. 	{
  48. 		triple_ = next(triple_.x, triple_.y, triple_.z);
  49. 		return *this;
  50. 	}
  51. };
  52.  
  53. int main()
  54. {
  55. 	copy_n(triple_iterator_t(), 10, std::ostream_iterator<triple_t>(std::cout, "\n"));
  56. }
Success #stdin #stdout 0s 3296KB
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stdin
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Standard input is empty
stdout
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3, 4, 5
6, 8, 10
5, 12, 13
9, 12, 15
8, 15, 17
12, 16, 20
7, 24, 25
15, 20, 25
10, 24, 26
20, 21, 29
https://ideone.com/oyNk1O
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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