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  1. #include <chrono>
  2. #include <iostream>
  3. #include <random>
  4. #include <vector>
  5.  
  6.  
  7. class stopwatch
  8. {
  9.   std::chrono::time_point<std::chrono::high_resolution_clock> last_;
  10. public:
  11.   stopwatch()
  12.   {
  13.     reset();
  14.   }
  15.   void reset()
  16.   {
  17.     last_ = std::chrono::high_resolution_clock::now();
  18.   }
  19.   std::chrono::microseconds elapsed() const
  20.   {
  21.     auto t = std::chrono::high_resolution_clock::now();
  22.     return std::chrono::duration_cast<std::chrono::microseconds>(t - last_);
  23.   }
  24.   std::chrono::microseconds tick()
  25.   {
  26.     auto t = std::chrono::high_resolution_clock::now();
  27.     auto elapsed = std::chrono::duration_cast<std::chrono::microseconds>(t - last_);
  28.     last_ = t;
  29.     return elapsed;
  30.   }
  31. }; 
  32.  
  33. template <std::size_t N, typename Iterator>
  34. void foo(Iterator begin, Iterator end)
  35. {
  36. 	for (; begin != end; ++begin)
  37. 	{
  38. 		*begin *= N;
  39. 		*begin *= N;
  40. 		*begin *= N;
  41. 		*begin *= N;
  42. 		*begin *= N;
  43. 	}
  44. }
  45.  
  46. int main()
  47. {
  48.         std::vector<unsigned> v;
  49.         std::default_random_engine e;
  50.  
  51.         for (unsigned i = 5000000; i-- != 0; )
  52.                 v.push_back(e());
  53.  
  54.         stopwatch w;
  55.         foo<77>(v.begin(), v.end());
  56.         std::cout << "Time: " << w.elapsed().count() / 1000000.0 << '\n';
  57.         std::cout << v[e() % v.size()] << '\n';
  58.  
  59.         w.reset();
  60.         foo<31>(v.begin(), v.end());
  61.         std::cout << "Time: " << w.elapsed().count() / 1000000.0 << '\n';
  62.         std::cout << v[e() % v.size()] << '\n';
  63. }
Success #stdin #stdout 0.12s 2960KB
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Standard input is empty
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Time: 0.010809
4273669408
Time: 0.010802
4123921301
https://ideone.com/Ro59c
language:
C++14 (gcc 8.3)
created:
13 years ago
visibility:
public

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