What is AVL Tree | AVL Tree meaning

An AVL is a self-balancing Binary Search Tree (BST) where the difference between the heights of left and right subtrees of any node cannot be more than one.

KEY POINTS

• It is height balanced tree
• It is a binary search tree
• It is a binary tree in which the height difference between the left subtree and right subtree is almost one
• Height is the maximum depth from root to leaf

Characteristics of AVL Tree:

• It follows the general properties of a Binary Search Tree.
• Each subtree of the tree is balanced, i.e., the difference between the height of the left and right subtrees is at most 1.
• The tree balances itself when a new node is inserted. Therefore, the insertion operation is time-consuming

Application of AVL Tree:

• Most in-memory sets and dictionaries are stored using AVL trees.
• Database applications, where insertions and deletions are less common but frequent data lookups are necessary, also frequently employ AVL trees.
• In addition to database applications, it is employed in other applications that call for better searching.
• Most STL implementations of the ordered associative containers (sets, multisets, maps and multimaps) use red-black trees instead of AVL trees.

Advantages of AVL Tree:

• AVL trees can self-balance.
• It also provides faster search operations.
• AVL trees also have balancing capabilities with a different type of rotation
• Better searching time complexity than other trees, such as the binary Tree.
• Height must not be greater than log(N), where N is the total number of nodes in the Tree.

Disadvantages of AVL Tree:

• AVL trees are difficult to implement
• AVL trees have high constant factors for some operations.

Maximum & Minimum number of Nodes

Maximum number of nodes = 2^H+1  – 1

Minimum number of nodes of height H = min no of nodes of height (H-1) + min no of nodes of height(H-2) + 1

where H(0)=1

              H(1)=2

What else can you read?

• Introduction to AVL Tree
• Insertion in AVL Tree
• Deletion in an AVL Tree