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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_;
  21.  
  22. 	static triple_t next(unsigned x, unsigned y, unsigned z)
  23. 	{
  24. 		while (true)
  25. 		{
  26. 			while (true)
  27. 			{
  28. 				while (true)
  29. 				{					
  30. 					if (y == z) break;
  31. 					++y;
  32. 					if (x * x + y * y == z * z) return {x, y, z};
  33. 				}
  34. 				if (x == z) break;
  35. 				++x;
  36. 				y = x;
  37. 			}
  38. 			++z;
  39. 			x = 1;
  40. 		}	
  41. 	}
  42.  
  43. public:
  44. 	triple_iterator_t() : triple_{1, 1, 1}
  45. 	{
  46. 		++(*this);
  47. 	}
  48.  
  49. 	triple_t operator *()
  50. 	{
  51. 		return triple_;
  52. 	}
  53.  
  54. 	triple_iterator_t & operator ++()
  55. 	{
  56. 		triple_ = next(triple_.x, triple_.y, triple_.z);
  57. 		return *this;
  58. 	}
  59. };
  60.  
  61. int main()
  62. {
  63. 	copy_n(triple_iterator_t(), 10, std::ostream_iterator<triple_t>(std::cout, "\n"));
  64. }
Success #stdin #stdout 0s 3340KB
comments (?)
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/B8p7m0
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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