# What Is an AVL Tree in Data Structure and Algorithm?

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Angela Bailey

An AVL tree is a self-balancing binary search tree in data structure and algorithm. It is named after its inventors, Adelson-Velsky and Landis. The AVL tree ensures that the height difference between its left and right subtrees does not exceed one, thus maintaining a balanced structure.

## Why AVL Trees?

Binary search trees are widely used data structures for efficient searching, insertion, and deletion operations. However, if we perform a series of insertions or deletions in a binary search tree without any balance criteria, the tree’s height can become highly imbalanced. As a result, the performance of search operations deteriorates from O(log n) to O(n), where n is the number of elements in the tree.

To overcome this issue, AVL trees were introduced. By ensuring that the height difference between the left and right subtrees is at most one, AVL trees maintain a balanced structure that guarantees efficient operations regardless of the order of insertions or deletions.

## Properties of an AVL Tree

An AVL tree possesses the following properties:

• Balance Factor: The balance factor of a node is defined as the height difference between its left and right subtrees. It can be -1, 0, or 1 for each node in an AVL tree.
• Height: The height of an AVL tree is defined as the maximum height among all its nodes. It represents how well-balanced the overall structure is.

## Operations on an AVL Tree

An AVL tree supports various operations including:

• Insertion: When inserting a new element into an AVL tree, it follows similar steps as in a binary search tree. However, after insertion, the tree might become unbalanced.

To restore balance, rotation operations are performed to maintain the AVL property.

• Deletion: Deleting a node from an AVL tree also involves similar steps as in a binary search tree. After deletion, the tree may lose its balance, requiring rotations to restore it.
• Search: Searching for an element in an AVL tree is performed using the same approach as in a binary search tree. The balanced structure ensures efficient search operations with a time complexity of O(log n).

The advantages of using AVL trees include:

• Efficient Operations: AVL trees maintain a balanced structure, ensuring efficient search, insertion, and deletion operations with a time complexity of O(log n).
• Predictable Performance: Unlike regular binary search trees, AVL trees offer predictable performance regardless of the order of insertions or deletions.

## Conclusion

An AVL tree is an important data structure that ensures efficient searching and manipulation operations by maintaining a balanced structure. By limiting the height difference between its left and right subtrees to at most one, it guarantees predictable performance for various algorithms and applications.

If you are interested in learning more about data structures and algorithms, exploring further into AVL trees is highly recommended!