private void updateHeight(AVLTreeNode<E> node) {
if (node.left == null && node.right == null) node.height = 0;
else if (node.left == null) node.height = 1 + ((AVLTreeNode<E>) (node.right)).height;
else if (node.right == null) node.height = 1 + ((AVLTreeNode<E>) (node.left)).height;
else
node.height =
1
+ Math.max(
((AVLTreeNode<E>) (node.right)).height, ((AVLTreeNode<E>) (node.left)).height);
}