Find element occuring once when all other are present thrice.cpp

class Solution {
  public:
    int singleElement(int arr[] ,int N) {
        // code here
        map<int,int>mp;
        for(int i=0;i<N;i++)
        {
            mp[arr[i]]++;
        }
        for(auto it:mp)
        {
            if(it.second==1)
            return it.first;
        }
    }
};