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  1. #include <iostream>
  2. #include <sstream>
  3. #include <vector>
  4. #include <string>
  5. #include <map>
  6. #include <unordered_map>
  7. #include <sys/time.h>
  8. using namespace std;
  9.  
  10. class StopWatch {
  11. public:
  12. 	StopWatch(string title) 
  13. 	: title_(title) {
  14. 		gettimeofday(&s_, 0);
  15. 	}
  16. 	~StopWatch() {
  17. 		gettimeofday(&e_, 0);
  18. 		printf("%s time = %lf\n", title_.c_str(), (e_.tv_sec - s_.tv_sec) + (e_.tv_usec - s_.tv_usec)*1.0E-6);
  19. 	}
  20. private:
  21.     struct timeval s_, e_;
  22.     string title_;
  23. };
  24.  
  25. const int COUNT = 100000;
  26.  
  27. int main() {
  28. 	// your code goes here
  29. 	{
  30. 		StopWatch sw("vector");
  31. 		std::vector<int> v;
  32. 		for (int i = 0; i < COUNT; i++) {
  33. 			v.push_back(i);
  34. 		}
  35. 	}
  36. 	{
  37. 		StopWatch sw("reserved vector");
  38. 		std::vector<int> v;
  39. 		v.reserve(COUNT);
  40. 		for (int i = 0; i < COUNT; i++) {
  41. 			v.push_back(i);
  42. 		}
  43. 	}
  44. 	std::map<std::string, int> m;
  45. 	{
  46. 		StopWatch sw("map set");
  47. 		for (int i = 0; i < COUNT; i++) {
  48. 			std::stringstream ss;
  49. 			ss << i << ":";
  50. 			m[ss.str()] = i;
  51. 		}
  52. 	}
  53. 	std::unordered_map<std::string, int> um;
  54. 	{
  55. 		StopWatch sw("unordered map set");
  56. 		for (int i = 0; i < COUNT; i++) {
  57. 			std::stringstream ss;
  58. 			ss << i << ":";
  59. 			um[ss.str()] = i;
  60. 		}
  61. 	}
  62. 	{
  63. 		StopWatch sw("map get");
  64. 		int total = 0;
  65. 		for (int i = 0; i < COUNT; i++) {
  66. 			std::stringstream ss;
  67. 			ss << i << ":";
  68. 			total += m[ss.str()];
  69. 		}
  70. 	}
  71. 	{
  72. 		StopWatch sw("unordered map get");
  73. 		int total = 0;
  74. 		for (int i = 0; i < COUNT; i++) {
  75. 			std::stringstream ss;
  76. 			ss << i << ":";
  77. 			total += um[ss.str()];
  78. 		}
  79. 	}
  80. 	return 0;
  81. }
Success #stdin #stdout 0.95s 13536KB
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stdin
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Standard input is empty
stdout
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vector time = 0.001062
reserved vector time = 0.000563
map set time = 0.245256
unordered map set time = 0.224707
map get time = 0.260892
unordered map get time = 0.204241
https://ideone.com/kzhZsv
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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