LeetCode: Single Number

/**
 * 
 */
package solution;

import java.util.Arrays;

/**
 * @author whh
 * 
 *         Given an array of integers, every element appears twice except for
 *         one. Find that single one.
 * 
 *         Note: Your algorithm should have a linear runtime complexity. Could
 *         you implement it without using extra memory?
 * 
 */
public class SingleNumber {

    /**
     * @param args
     */
    public static void main(String[] args) {
        int[] A1 = { 1 };
        int[] A2 = { 1,2,3,4,1,2,3 };
        int[] A3 = { 1,1,2,4,2,4,3,5,3 };
        System.out.println(singleNumber(A1));
        System.out.println(singleNumber(A2));
        System.out.println(singleNumber(A3));
    }

    /**
     * @param A
     * @return
     */
    public static int singleNumber(int[] A) {
        Arrays.sort(A);
        int ret = 0;
        for (int i = 0; i < A.length; i = i + 2) {
            if (i == A.length - 1) {
                ret = A[i];
                break;
            } else if (A[i] != A[i + 1]) {
                ret = A[i];
                break;
            }
        }
        return ret;
    }
}