260. Single Number III

class Solution {public:    vector<int> singleNumber(vector<int>& nums) {        unordered_map<int,int> m;        for(int i=0;i<nums.size();i++)        {            m[nums[i]]++;        }        vector<int> ret;        for(auto it=m.begin();it!=m.end();it++)        {            if((*it).second==1)            {                ret.push_back((*it).first);                if(ret.size()==2)                    break;            }        }        return ret;    }};