137. Single Number II.cpp

class Solution {
public:
    int singleNumber(vector<int>& nums) {
        unordered_map<int,int> mp;
        for(auto i:nums)
        {
            mp[i]++;
        }
        for(auto it:mp)
        {
            if(it.second==1)
            {
                return it.first;
            }
        }
        return 0;
        
    }
};