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  1. import java.io.*;
  2.  
  3. // Problem Description: 
  4. // In an array, all numbers appear three times except one which only
  5. // appears once. Please find the unique number.
  6.  
  7. class Ideone
  8. {
  9. 	public static int FindNumberAppearingOnce(int[] numbers) {
  10. 		int[] bitSum = new int[32];
  11. 		for(int i = 0; i < 32; ++i) {
  12. 			bitSum[i] = 0;
  13. 		}
  14.  
  15. 		for(int i = 0; i < numbers.length; ++i) {
  16. 			int bitMask = 1;
  17. 			for(int j = 31; j >= 0; --j) {
  18. 				int bit = numbers[i] & bitMask;
  19. 				if(bit != 0) {
  20. 					bitSum[j] += 1;
  21. 				}
  22.  
  23. 				bitMask = bitMask << 1;
  24. 			}
  25. 		}
  26.  
  27. 		int result = 0;
  28. 		for(int i = 0; i < 32; ++i) {
  29. 			result = result << 1;
  30. 			result += bitSum[i] % 3;
  31. 		}
  32.  
  33. 		return result;
  34. 	}
  35.  
  36. 	//////////////////////////////////////////////////////////////
  37. 	// Test Code Begins:
  38. 	//////////////////////////////////////////////////////////////
  39. 	private static void test(String testName, int[] numbers, int expected) {
  40. 		int result = FindNumberAppearingOnce(numbers);
  41. 		if(result == expected) {
  42. 			System.out.println(testName + " passed.");
  43. 		}
  44. 		else {
  45. 			System.out.println(testName + " FAILED.");
  46. 		}
  47. 	}
  48.  
  49. 	private static void test1() {
  50. 		int[] numbers = {1, 1, 2, 2, 2, 1, 3};
  51. 		int expected = 3;
  52. 		test("Test1", numbers, expected);
  53. 	}
  54.  
  55. 	private static void test2() {
  56. 		int[] numbers = {4, 3, 3, 2, 2, 2, 3};
  57. 		int expected = 4;
  58. 		test("Test2", numbers, expected);
  59. 	}
  60.  
  61. 	private static void test3() {
  62. 		int[] numbers = {4, 4, 1, 1, 1, 7, 4};
  63. 		int expected = 7;
  64. 		test("Test3", numbers, expected);
  65. 	}
  66.  
  67. 	private static void test4() {
  68. 		int[] numbers = {-10, 214, 214, 214};
  69. 		int expected = -10;
  70. 		test("Test4", numbers, expected);
  71. 	}
  72.  
  73. 	private static void test5() {
  74. 		int[] numbers = {-209, 3467, -209, -209};
  75. 		int expected = 3467;
  76. 		test("Test5", numbers, expected);
  77. 	}
  78.  
  79. 	private static void test6() {
  80. 		int[] numbers = {1024, -1025, 1024, -1025, 1024, -1025, 1023};
  81. 		int expected = 1023;
  82. 		test("Test6", numbers, expected);
  83. 	}
  84.  
  85. 	private static void test7() {
  86. 		int[] numbers = {-1024, -1024, -1024, -1023};
  87. 		int expected = -1023;
  88. 		test("Test7", numbers, expected);
  89. 	}
  90.  
  91. 	public static void main (String[] args) {
  92. 		test1();
  93. 		test2();
  94. 		test3();
  95. 		test4();
  96. 		test5();
  97. 		test6();
  98. 		test7();
  99. 	}
  100. }
Success #stdin #stdout 0.07s 380160KB
comments (?)
stdin 
int
stdout 
Test1 passed.
Test2 passed.
Test3 passed.
Test4 passed.
Test5 passed.
Test6 passed.
Test7 passed.
https://ideone.com/tTk3RX
Find the number appearing once
language:
Java (HotSpot 12)
created:
11 years ago
visibility:
public

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