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  1. #include <iostream>
  2. #include <iomanip>
  3. #include <chrono>
  4.  
  5. using namespace std;
  6.  
  7. class muTimer
  8. {
  9.     using Clock = std::chrono::high_resolution_clock;
  10.     bool active = false;
  11.     Clock::duration   duration_;
  12.     Clock::time_point start_ = Clock::now(), stop_ = Clock::now();
  13.  
  14.     muTimer(const muTimer&)             = delete;
  15.     muTimer& operator=(const muTimer&)  = delete;
  16. public:
  17.     using ns       = std::chrono::nanoseconds;
  18.     using mks      = std::chrono::microseconds;
  19.     using ms       = std::chrono::milliseconds;
  20.     muTimer() { reset(); start(); }
  21.     ~muTimer() = default;
  22.     muTimer& reset()
  23.     {
  24.         duration_ = std::chrono::nanoseconds(0);
  25.         active    = false;
  26.         return *this;
  27.     }
  28.     muTimer& start()
  29.     {
  30.         if (!active)
  31.         {
  32.             start_ = Clock::now();
  33.             active = true;
  34.         }
  35.         return *this;
  36.     }
  37.     muTimer& stop()
  38.     {
  39.         if (active)
  40.         {
  41.             stop_      = Clock::now();
  42.             duration_ += stop_ - start_;
  43.             active     = false;
  44.         }
  45.         return *this;
  46.     }
  47.     template<typename T = mks>
  48.         unsigned long long duration()
  49.     {
  50.         return static_cast<unsigned long long>
  51.             (std::chrono::duration_cast<T>(stop_-start_).count());
  52.     }
  53. };
  54.  
  55. long long fibR(unsigned int N)
  56. {
  57.     if (N < 2) return 1;
  58.     return fibR(N-1) + fibR(N-2);
  59. }
  60.  
  61. long long fibI(unsigned int N)
  62. {
  63.     if (N < 2) return 1;
  64.     long long f0 = 1, f1 = 1;
  65.     for(unsigned int i = 2; i <= N; ++i)
  66.     {
  67.         long long f = f0 + f1;
  68.         f0 = f1;
  69.         f1 = f;
  70.     }
  71.     return f1;
  72. }
  73.  
  74. int main(int argc, const char * argv[])
  75. {
  76.     for(unsigned int N = 3; N < 35; N += 3)
  77.     {
  78.         unsigned long long F;
  79.         {
  80.             muTimer mt;
  81.             for(int i = 0; i < 100; ++i)
  82.                 F = fibI(N);
  83.             unsigned long long t = mt.stop().duration();
  84.             cout << "N(i) = " << setw(3) << N << setw(10) << F << setw(10) << t << " mks\n";
  85.         }
  86.         {
  87.             muTimer mt;
  88.             for(int i = 0; i < 100; ++i)
  89.                 F = fibR(N);
  90.             unsigned long long t = mt.stop().duration();
  91.             cout << "N(r) = " << setw(3) << N << setw(10) << F << setw(10) << t << " mks\n";
  92.         }
  93.     }
  94. }
  95.  
  96.  
Success #stdin #stdout 1.42s 4532KB
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stdin
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Standard input is empty
stdout
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N(i) =   3         3         0 mks
N(r) =   3         3         1 mks
N(i) =   6        13         0 mks
N(r) =   6        13         5 mks
N(i) =   9        55         1 mks
N(r) =   9        55        22 mks
N(i) =  12       233         2 mks
N(r) =  12       233       123 mks
N(i) =  15       987         2 mks
N(r) =  15       987       397 mks
N(i) =  18      4181         3 mks
N(r) =  18      4181      1710 mks
N(i) =  21     17711         3 mks
N(r) =  21     17711      7261 mks
N(i) =  24     75025         4 mks
N(r) =  24     75025     27304 mks
N(i) =  27    317811         3 mks
N(r) =  27    317811     91201 mks
N(i) =  30   1346269         3 mks
N(r) =  30   1346269    257996 mks
N(i) =  33   5702887         2 mks
N(r) =  33   5702887   1025391 mks
https://ideone.com/rfjifS
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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