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  1. #include <stdlib.h>
  2. #include <math.h>
  3. #include <time.h>
  4. #include <iostream>
  5. #include <vector>
  6.  
  7. static bool isGet(int captureProbability)
  8. {
  9. 	const int r = rand() % 100;
  10. 	return r < captureProbability;
  11. }
  12.  
  13. int main()
  14. {
  15. 	const int probablility = 12; /*捕獲率*/
  16. 	const int captureNum = 50; /*１セット捕獲率*/
  17. 	const int trialNum = 10000; /*試行回数*/
  18.  
  19. 	srand(time(0));
  20.  
  21. 	std::vector<int> data(trialNum);
  22. 	for(int i = 0 ; i < trialNum ; ++i)
  23. 	{
  24. 		int capture = 0;
  25. 		for(int j = 0 ; j < captureNum ; ++j)
  26. 		{
  27. 			if(isGet(probablility))
  28. 				++capture;
  29. 		}
  30. 		data[i] = capture;
  31. 	}
  32.  
  33. 	int sum = 0;
  34. 	for(int i = 0 ; i < trialNum ; ++i)
  35. 	{
  36. 		sum += data[i];
  37. 	}
  38. 	const double average = static_cast<double>(sum) / static_cast<double>(trialNum);
  39.  
  40. 	double scattering = 0.0;
  41. 	for(int i = 0 ; i < trialNum ; ++i)
  42. 	{
  43. 		const double dif = average - static_cast<double>(data[i]);
  44. 		scattering += dif * dif;
  45. 	}
  46. 	scattering /= trialNum;
  47.  
  48. 	const double standardDeviation = sqrt(scattering);
  49.  
  50. 	std::cout << "捕獲率12%のモンスターを５０匹倒したとき、" << std::endl;
  51. 	std::cout << "68%の確率で、" << average - standardDeviation << "～" << average + standardDeviation << "匹捕獲できる" << std::endl;
  52. 	std::cout << "95%の確率で、" << average - standardDeviation * 2.0 << "～" << average + standardDeviation * 2.0 << "匹捕獲できる" << std::endl;
  53.  
  54. 	return 0;
  55. }
  56.  
Success #stdin #stdout 0.03s 2856KB
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捕獲率12%のモンスターを５０匹倒したとき、
68%の確率で、3.68787～8.26713匹捕獲できる
95%の確率で、1.39825～10.5568匹捕獲できる
https://ideone.com/shi0z
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
public

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