1356. Sort Integers by The Number of 1 Bits

class Solution {
public:
    vector<int> sortByBits(vector<int>& arr) {
       vector <pair<int,int>>v;
       for(int i=0; i<arr.size();i++)
       {
           int cnt=0;
           int m=arr[i];
           while(m)
           {
               cnt+=m&1;
               m=m>>1;

           }
           v.push_back({cnt,arr[i]});
       }
       sort(v.begin(),v.end());
      for(int i=0; i<arr.size(); i++)
      {
          arr[i]=v[i].second;
      }

     return arr;     
    }
};