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  1. class Main {
  2. 	public static void main(String[] args) {
  3. 		System.out.println("出題者が箱を選んでその箱がはずれだったとき");
  4. 		case1();
  5. 		System.out.println("");
  6. 		System.out.println("出題者がはずれの箱を選んだとき");
  7. 		case2();
  8. 	}
  9.  
  10. 	static void case1() {
  11. 		int count=0;
  12. 		int changed = 0;
  13. 		int unchanged = 0;
  14. 		java.util.Random rm = new java.util.Random();
  15.  
  16. 		while (count < 10000) {
  17. 			int atari = rm.nextInt(3);
  18. 			int select = rm.nextInt(3);
  19.  
  20. 			int open;
  21. 			do {
  22. 				open = rm.nextInt(3);
  23. 			} while (open == select);
  24.  
  25. 			int select2;
  26. 			do {
  27. 				select2 = rm.nextInt(3);
  28. 			} while (select2 == open || select2 == select);
  29.  
  30. 			if (open != atari) {
  31. 				if (select == atari) {
  32. 					unchanged++;
  33. 				} else if (select2 == atari) {
  34. 					changed++;
  35. 				}
  36. 				count++;
  37. 			}
  38. 		}
  39. 		System.out.println("箱を変えなかったとき：" + ((double)unchanged/count*100) + "%");
  40. 		System.out.println("箱を変えたとき：" + ((double)changed/count*100) + "%");
  41. 	}
  42.  
  43. 	static void case2() {
  44. 		int count=0;
  45. 		int changed = 0;
  46. 		int unchanged = 0;
  47. 		java.util.Random rm = new java.util.Random();
  48.  
  49. 		while (count < 10000) {
  50. 			int atari = rm.nextInt(3);
  51. 			int select = rm.nextInt(3);
  52.  
  53. 			int open;
  54. 			do {
  55. 				open = rm.nextInt(3);
  56. 			} while (open == select || open == atari);
  57.  
  58. 			int select2;
  59. 			do {
  60. 				select2 = rm.nextInt(3);
  61. 			} while (select2 == open || select2 == select);
  62.  
  63. 			if (select == atari) {
  64. 				unchanged++;
  65. 			} else if (select2 == atari) {
  66. 				changed++;
  67. 			}
  68. 			count++;
  69. 		}
  70. 		System.out.println("箱を変えなかったとき：" + ((double)unchanged/count*100) + "%");
  71. 		System.out.println("箱を変えたとき：" + ((double)changed/count*100) + "%");
  72. 	}
  73.  
  74. }
Success #stdin #stdout 0.05s 245760KB
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Standard input is empty
stdout
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出題者が箱を選んでその箱がはずれだったとき
箱を変えなかったとき：49.669999999999995%
箱を変えたとき：50.33%

出題者がはずれの箱を選んだとき
箱を変えなかったとき：34.38%
箱を変えたとき：65.62%
https://ideone.com/CVS7m
language:
Java (HotSpot 12)
created:
12 years ago
visibility:
public

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