void printTreeBfs(tree *tr)
{
    queue<tree*> bfs;
    bfs.push(tr);
    tree *check;
    while (!bfs.empty())
    {
        check = bfs.front();
        cout << check->data << " ";
        bfs.pop();
        if (check->left)
            bfs.push(check->left);
        if (check->right)
            bfs.push(check->right);
    }
    cout << endl;
}