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  1. // compile with
  2. // g++-4.8 -o main_gcc -O3 -std=c++11 -Wall -Wextra -pedantic -Werror main.cpp square.cpp
  3. // clang++ -o main_clang -O3 -std=c++11 -Wall -Wextra -pedantic -Werror main.cpp square.cpp
  4.  
  5. #include <algorithm>
  6. #include <ctime>
  7. #include <functional>
  8. #include <iostream>
  9. #include <iterator>
  10. #include <numeric>
  11. #include <string>
  12. #include <vector>
  13.  
  14. using namespace std;
  15.  
  16. typedef vector<int> Vec;
  17. //int n = 8;
  18. int n = 1000000;
  19. size_t max_print = 10;
  20. int shift = 3;
  21. int runs = 400;
  22.  
  23. void shift_rev( Vec& v, size_t a )
  24. {
  25. 	reverse( v.begin(), v.end() );
  26. 	reverse( v.begin(), v.begin() + a );
  27. 	reverse( v.begin() + a, v.end() );
  28. }
  29.  
  30. void shift_swap(Vec& v, size_t a)
  31. {
  32. 	size_t max_s = v.size() / a;
  33. 	for( size_t s = 1; s < max_s; ++s )
  34. 		for( size_t i = 0; i < a; ++i )
  35. 			swap( v[i], v[s*a+i] );
  36. 	for( size_t i = 0; i < a; ++i )
  37. 		swap( v[i], v[(max_s*a+i) % v.size()] );
  38. }
  39.  
  40. void print(const Vec& v)
  41. {
  42. 	copy( v.begin(), v.end(), ostream_iterator<int>( cout, ",") );
  43. 	cout << endl;
  44. }
  45.  
  46. void test( Vec v, function<void(Vec&, size_t)> f, const string& name )
  47. {
  48. 	unsigned int startTime = clock();
  49.  
  50. 	for ( int i = 0; i < runs; ++i )
  51. 		f( v, shift % v.size() );
  52.  
  53. 	// sum the result to prevent the optimizer from removing everything.
  54. 	auto check = accumulate( v.begin(), v.end(), 0 );
  55.  
  56. 	if ( v.size() <= max_print )
  57. 		print( v );
  58.  
  59.     double duration = static_cast<double>(clock() - startTime) / CLOCKS_PER_SEC;
  60.  
  61. 	cout << name << " (check: " << check << "), duration: " << duration << endl;
  62. }
  63.  
  64. int main()
  65. {
  66. 	vector<int> v;
  67. 	v.reserve( n );
  68.  
  69. 	for (int i = 1; i <= n; ++i )
  70. 		v.push_back(i);
  71.  
  72. 	if ( v.size() <= max_print )
  73. 		print( v );
  74.  
  75. 	test( v, &shift_rev, "rev " );
  76. 	test( v, &shift_swap, "swap" );
  77. }
Success #stdin #stdout 2.22s 3476KB
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stdin
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Standard input is empty
stdout
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rev  (check: 1784293664), duration: 1.24
swap (check: 1784293664), duration: 0.96
https://ideone.com/St7wPv
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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