Function topview

CPP/Trees/TopView_of_tree.cpp:27–68

function should print the topView of the binary tree

// function should print the topView of
// the binary tree
void topview(Node *root)
{
    if (root == NULL)
        return;
    queue<Node *> q;
    map<int, int> m;
    int hd = 0;
    root->hd = hd;

    // push node and horizontal distance to queue
    q.push(root);

    cout << "The top view of the tree is : \n";

    while (q.size())
    {
        hd = root->hd;

        // count function returns 1 if the container
        // contains an element whose key is equivalent
        // to hd, or returns zero otherwise.
        if (m.count(hd) == 0)
            m[hd] = root->data;
        if (root->left)
        {
            root->left->hd = hd - 1;
            q.push(root->left);
        }
        if (root->right)
        {
            root->right->hd = hd + 1;
            q.push(root->right);
        }
        q.pop();
        root = q.front();
    }

    for (auto i = m.begin(); i != m.end(); i++)
    {
        cout << i->second << " ";
    }
}


int main()