A no-arg constructor is shown in Program . This constructor creates an empty AVL tree. The height field is set to the value -1, which is consistent with the empty tree. Notice that according to Definition , the empty tree is AVL balanced. Therefore, the result is a valid AVL tree. Clearly, the running time of the constructor is O(1).
Program: AVLTree class constructor, getHeight, adjustHeight, and getBalanceFactor methods.