136. Single Number

    /*
     * 136. Single Number
     * 2016-5-22 by Mingyang
     */
    public int singleNumber(int[] nums) {
        int len=nums.length;
        if(nums==null||len==0)
          return 0;
          int res=0;
        for(int i=0;i<len;i++){
            res=res^nums[i];
        }
        return res;
    }