[LeetCode] NO. 136 Single Number

[题目] 

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?

 

[题目解析] 如果对空间没有要求，可以使用map来解决。如果有要求的话，这里可以巧妙使用异或运算进行处理。

    public int singleNumber(int[] nums) {
        if(null != nums && nums.length > 0){
            int result = nums[0];
            for(int i = 1; i < nums.length; i++){
                result = result ^ nums[i];
            }
            return result;
        }
        return -1;
    }