Given a Binary Tree, print Left view of it. Left view of a Binary Tree is set of nodes visible when tree is visited from Left side. The task is to complete the function leftView(), which accepts root of the tree as argument. code example

Example: gfg left view of tree

/* This is not the entire code. It's just the function which implements 
   bottom view. You need to write required code. */

// Obj class is used to store node with it's distance from parent.
class Obj
{
    public:
        Node *root;
        int dis; // distance from parent node. distance of root node will be 0.

        Obj(Node *node, int dist)
        {
            root = node;
            dis = dist;
        }
};

// function to print left view of tree.
void leftView(Node *root)
{
    queue<Obj*> q;
    q.push(new Obj(root, 0));
    map<int,int> m;

    while(!q.empty())
    {
        Obj *ob = q.front();
        q.pop();

        if(m.find(ob->dis) == m.end())
            m[ob->dis] = ob->root->data;

        if(ob->root->left != NULL)
            q.push(new Obj(ob->root->left, ob->dis+1)); 
        if(ob->root->right != NULL)
            q.push(new Obj(ob->root->right, ob->dis+1));
    }

    for(auto it=m.begin(); it!=m.end(); it++)
        cout << it->second << "\t";

    cout << endl;
}