This AVL tree is unbalanced, since the balance factor for node 6 is -2. Instead, add a variable to each node which stores the height of the tree rooted at that node. AVL Tree Rotations. I have an assignment, to implement a method which prints out the balance factor of all the internal nodes of the binary tree t. I have tried to do it, but I needed three methods.. AVL tree checks the height of the left and the right sub-trees and assures that the difference is not more than 1. I’ve marked the balance factor … And the second part is getting the balance factor of a sub-tree in an AVL tree, I've got no problem understanding the concept, "get the height of your L and R sub-trees and subtract R from L". The above height-balancing scheme is used in AVL trees. Calculating it each time would completely destroy the advantages of using an AVL tree in the first place. For a given node N, the absolute difference between the heights of its left and right sub tree is either zero or one. In Data Structures, AVL tree (Adelson-Velsky and Landis tree) is a height-balanced binary search tree in which difference between the heights of left subtree and right subtree can be atmost 1. I think there should be one and I am only able to print out the balance factor of the root, I think this should be for every node of tree t? But we can fix it! It is a binary search tree where each node associated with a balance factor. Then, whenever you need to know the balance factor of a node you simply use the definition of balance factor and the heights of its children. Sandeep Verma; Articles . Rebalancing operates on a root node and is only carried out depending on the balance factor … Each node of the AVL Tree maintains a specific relation between its left and right sub trees. The height of an AVL tree is always O(Logn) where n is the number of nodes in the tree. This difference is called the Balance Factor. A non-empty binary tree T is balanced if: 1) Left subtree of T is balanced 2) Right subtree of T is balanced 3) The difference between heights of left subtree and right subtree is not more than 1. And this is defined as something like this: BALANCE = NODE[L][HEIGHT] - NODE[R][HEIGT] This step is what makes an AVL tree an AVL tree and is responsible for maintaining log(n) height. How to Calculate AVL Tree Balance Factor ? The difference between the heights can be termed as the balance factor. The diagram below shows two trees, one of them is height-balanced and other is not. Therefore, we can calculate the new balances of "A" and "B" as follows (ht is the height function): NewBal(A) = ht(b) - … For purposes of implementing an AVL tree, and gaining the benefit of having a balanced tree we will define a tree to be in balance if the balance factor is -1, 0, or 1. We define a Balance Factor for each node as the maximum height of the left node’s path minus the maximum height of the right node’s path. Have a look at this AVL tree. If the balance factor is zero then the tree is perfectly in balance. The "balance" of a tree is the height of its right subtree less the height of its left subtree. If after any modification in the tree, the balance factor becomes less than −1 or greater than +1, the subtree rooted at this node is unbalanced, and a rotation is needed. The balance factor of any node of an AVL tree is in the integer range [-1,+1].