LintCode-82.落单的数

public class Solution {
    /**
      *@param A : an integer array
      *return : a integer 
      */
    public int singleNumber(int[] A) {
        // Write your code here
        int a = 0;
        for(int i = 0; i < A.length; i++){
            a ^= A[i];  
        }
        return a;

    }
}