136. Single Number

      史上最水的題。。。當然如果用了sort...

      

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?

class Solution {
public:
    int singleNumber(vector<int>& nums) {
        if(nums.size()==1)
		return nums[0];
	    sort(nums.begin(),nums.end());
	   for(int i=0;i<nums.size()-1;i+=2)
	  {
		if(nums[i]!=nums[i+1])
	   		return nums[i];
      }
   	  return nums[nums.size()-1];
    }
};