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/************************************************************

    Following is the TreeNode class structure:

    template <typename T>
    class TreeNode
    {
    public:
        T data;
        TreeNode<T> *left;
        TreeNode<T> *right;

        TreeNode(T dat)
        {
            this->data = dat;
            left = NULL;
            right = NULL;
        }
    };

************************************************************/
#include<map>
#include<queue>
#include<vector>

/* first input of every horizontal distance array will be top node */
vector<int> getTopView(TreeNode<int> *root)
{
    vector<int> ans;
    if(root==NULL) return ans;

    map<int,int> topnode;  //(distance,topnode) //vector wont work for topnode
    queue<pair<TreeNode<int>*,int>> q; // (node,horizontal dsit)
    q.push(make_pair(root,0));
    
    while(!q.empty()){
        pair<TreeNode<int>*,int> front=q.front(); //getting the node
        q.pop(); //pop korte keno BHULE jasss???
        TreeNode<int>* tmp=front.first;
        int dist=front.second;

        if(topnode.find(dist)==topnode.end()){ //checking if its the first
            topnode[dist]=tmp->data;
        }

        if(tmp->left) q.push(make_pair(tmp->left,dist-1));
        if(tmp->right) q.push(make_pair(tmp->right,dist+1));
    }
    //now topnode has all topnodes in format (distance,node)
    
    for(auto i:topnode){
        ans.push_back(i.second);
    }
    return ans;
}