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  1. #include <iostream>
  2. #include <chrono>
  3.  
  4. using namespace std;
  5.  
  6. double calc1(const int* a, const int* b) {
  7.  
  8. 	auto start = chrono::system_clock::now();
  9.  
  10. 	int* c = new int[10000000];
  11.  
  12. 	for (int i = 0; i < 10000000; i++)
  13. 		c[i] = a[i] + b[i];
  14.  
  15. 	delete[] c;
  16.  
  17. 	return chrono::duration<double>( chrono::system_clock::now() -start).count();
  18. }
  19.  
  20. double calc2(const int*a, const int*b) {
  21.  
  22. 	auto start = chrono::system_clock::now();
  23.  
  24. 	int* c = new int[10000000];
  25.  
  26. 	for (int i = 0; i < 10000000; i+=4){
  27.  
  28. 		auto i0 = i;
  29. 		auto i1 = i+1;
  30. 		auto i2 = i+2;
  31. 		auto i3 = i+3;
  32.  
  33. 		c[i0] = a[i0] + b[i0];
  34. 		c[i1] = a[i1] + b[i1];
  35. 		c[i2] = a[i2] + b[i2];
  36. 		c[i3] = a[i3] + b[i3];
  37. 	}
  38.  
  39. 	delete[] c;
  40.  
  41. 	return chrono::duration<double>(chrono::system_clock::now() - start).count();
  42.  
  43. }
  44.  
  45. int main() {
  46. 	// your code goes here
  47. 	int* a = new int[10000000];
  48. 	int* b = new int[10000000];
  49.  
  50. 	std::cout << calc1(a, b) << '\n' << calc2(a, b);
  51.  
  52. 	delete[] a;
  53. 	delete[] b;
  54. }
Success #stdin #stdout 0.03s 15240KB
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0.0125982
0.018405
https://ideone.com/bj8N8a
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
secret

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