Leetcode[136]-Single Number

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?

比较简单，直接上代码：
Code(c++)

class Solution {
public:
    int singleNumber(vector<int>& nums) {
        int n = nums.size();

        sort(nums.begin(),nums.end());
        if(n==1) return nums[0];
        int i = 0;
        while(i<n) {
            if(nums[i] == nums[i+1])
                i = i+2;
            else
                return nums[i];
        }
        return 0;
    }
};