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  1. #include <iostream>
  2. #include <sys/time.h>	// gettimeofday()
  3. #include <climits>		// UINT_MAX
  4.  
  5. using namespace std;
  6.  
  7. #define NUMSTEPS UINT_MAX
  8.  
  9. int main(){
  10. 	timeval t1, t2, t3, t4;
  11. 	unsigned int a = 32, b = 64, c = 0, i = 0;
  12. 	double elapsedTime;
  13.  
  14. 	gettimeofday(&t1, NULL);
  15. 	for(i = 0; i < NUMSTEPS; ++i){
  16. 		swap(a, b);
  17. 	}
  18.  
  19. 	gettimeofday(&t2, NULL);
  20. 	for(i = 0; i < NUMSTEPS; ++i){
  21. 		a^=b;
  22. 		b^=a;
  23. 		a^=b;
  24. 	}
  25.  
  26. 	gettimeofday(&t3, NULL);
  27. 	for(i = 0; i < NUMSTEPS; ++i){
  28. 		c = b;
  29. 		b = a;
  30. 		a = c;
  31. 	}
  32. 	gettimeofday(&t4, NULL);
  33.  
  34. 	cout<<"NUMSTEPS = "<<NUMSTEPS<<endl;
  35. 	// compute and print the elapsed time in millisec
  36. 	elapsedTime = (t2.tv_sec - t1.tv_sec) * 1000.0;      // sec to ms
  37. 	elapsedTime += (t2.tv_usec - t1.tv_usec) / 1000.0;   // us to ms
  38. 	cout << "swap\t" << elapsedTime << " ms.\n";
  39.  
  40. 	elapsedTime = (t3.tv_sec - t2.tv_sec) * 1000.0;      // sec to ms
  41. 	elapsedTime += (t3.tv_usec - t2.tv_usec) / 1000.0;   // us to ms
  42. 	cout << "XOR\t" << elapsedTime << " ms.\n";
  43.  
  44. 	elapsedTime = (t4.tv_sec - t3.tv_sec) * 1000.0;      // sec to ms
  45. 	elapsedTime += (t4.tv_usec - t3.tv_usec) / 1000.0;   // us to ms
  46. 	cout << "+var\t" << elapsedTime << " ms.\n";
  47. 	cout<<a<<b<<c<<"\b\b\b\b\b\b";
  48. 	return 0;
  49. }
  50.  
Time limit exceeded #stdin #stdout 5s 3292KB
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https://ideone.com/bJK71K
language:
C++ (gcc 8.3)
created:
10 years ago
visibility:
secret

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