Problem
1. Write a method that returns the height of an AVL tree by tracing only one path to a leaf, not by investigating all the nodes in the tree.
2. Write a function that returns a pointer to the leftmost leaf closest to the root of a nonempty AVL tree. 3. Prove that the number of (single or double) rotations done in deleting a key from an AVL tree cannot exceed half the height of the tree