Bottom view of binary tree

#include <queue> 
class Solution {
  public:
    vector <int> bottomView(Node *root) {
        // Your Code Here
        vector <int> ans ; 
         queue < pair <Node *  , int> > q ; 
         map < int, int > m ; 
         q.push({root , 0}) ;
         while(!q.empty())
         {
             int sz = q.size() ; 
             for(int i = 0 ; i < sz ; i++)
             {
                 Node * f = q.front().first  ;
                 int l = q.front().second ; 
                 m[l] = f->data ; 
                 q.pop() ;
                 if(f->left)
                 {
                     q.push({f->left, l - 1}) ;
                 }
                 if(f->right)
                 {
                     q.push({f->right , l  + 1})  ;
                 }
                 
                 
             }
         }
    
        for(auto itr : m)
        {
            ans.push_back(itr.second) ;
        }
        return ans ; 
    }
};