LeetCode: Single Number II

 1 /** 2  *  3  */ 4 package solution; 5  6 import java.util.Arrays; 7  8 /** 9  * @author whh10  * 11  *         Given an array of integers, every element appears three times except12  *         for one. Find that single one.13  * 14  *         Note: Your algorithm should have a linear runtime complexity. Could15  *         you implement it without using extra memory?16  */17 public class SingleNumber2 {18 19     /**20      * @param args21      */22     public static void main(String[] args) {23         int[] A1 = { 1 };24         int[] A2 = { 1, 2, 3, 4, 1, 2, 3, 1, 2, 3 };25         int[] A3 = { 1, 1, 2, 4, 2, 4, 3, 5, 3, 1, 2, 3, 4 };26         int[] A4 = { 1, 1 };27         int[] A5 = { 1, 1, 1, 2, 2, 2, 3, 3 };28         System.out.println(singleNumber(A1));29         System.out.println(singleNumber(A2));30         System.out.println(singleNumber(A3));31         System.out.println(singleNumber(A4));32         System.out.println(singleNumber(A5));33     }34 35     /**36      * 37      * @param A38      * @return39      */40     public static int singleNumber(int[] A) {41         Arrays.sort(A);42         int ret = 0;43         for (int i = 0; i < A.length; i = i + 3) {44             if (i == A.length - 1 || i == A.length - 2) {45                 ret = A[i];46                 break;47             } else if (!(A[i] == A[i + 1] && A[i] == A[i + 2])) {48                 ret = A[i];49                 break;50             }51         }52         return ret;53     }54 55 }