# How do I search in AVL tree?

## How do I search in AVL tree?

Searching for a node in an AVL Tree is the same as with any BST. Start from the root of the tree and compare the key with the value of the node. If the key equals the value, return the node. If the key is greater, search from the right child, otherwise continue the search from the left child.

**How many cases of rotation are there for AVL trees?**

The key to an AVL tree is keeping it balanced when an insert or delete operation is performed. If we start with an AVL tree, then what is needed is either a single rotation or a double rotation (which is two single rotations) on the unbalanced node and that will always restore the balance property in O(1) time.

### How do I know when to rotate my AVL tree?

AVL tree may become unbalanced, if a node is inserted in the left subtree of the left subtree. The tree then needs a right rotation. As depicted, the unbalanced node becomes the right child of its left child by performing a right rotation.

**What is worst case time complexity of search operation in AVL tree?**

Therefore, searching in AVL tree has worst case complexity of O(log2n).

#### What is LL rotation in AVL tree?

The tree shown in following figure is an AVL Tree, however, we,need to insert an element into the left of the left sub-tree of A. the tree can become unbalanced with the presence of the critical node A. The node whose balance factor doesn’t lie between -1 and 1, is called critical node.

**How does the AVL tree differ from binary search tree?**

Differences between Binary Search tree and AVL tree Every AVL tree is also a binary tree because AVL tree also has the utmost two children. In BST, there is no term exists, such as balance factor. In the AVL tree, each node contains a balance factor, and the value of the balance factor must be either -1, 0, or 1.

## What are the different types of rotation in AVL tree?

The worst case space complexity is O(n) .

- AVL Insertion Process. Insertion in an AVL tree is similar to insertion in a binary search tree.
- Left Rotation (LL Rotation)
- Right Rotation (RR Rotation)
- Left-Right Rotation (LR Rotation)
- Right-Left Rotation (RL Rotation)

**What is RR rotation in AVL tree?**

If the node is inserted into the right of the right sub-tree of a node A and the tree becomes unbalanced then, in that case, RR rotation will be performed as shown in the following diagram. While the rotation, the node B becomes the root node of the tree.

### How do you rotate an AVL tree?

AVL Rotations

- L L rotation: Inserted node is in the left subtree of left subtree of A.
- R R rotation : Inserted node is in the right subtree of right subtree of A.
- L R rotation : Inserted node is in the right subtree of left subtree of A.
- R L rotation : Inserted node is in the left subtree of right subtree of A.

**How does rotation work in AVL tree?**

A single rotation applied when a node is inserted in the left subtree of a left subtree. In the given example, node C now has a balance factor of 2 after the insertion of node A. By rotating the tree right, node B becomes the root resulting in a balanced tree.

#### What is the time complexity of rotation in AVL tree?

Insertion and Deletion time complexity of AVL tree is O(log n) and the searching time complexity of the AVL tree is O(n) which makes it better than binary search tree and red-black tree.

**Why AVL trees are useful in search operation in large databases?**

Advantages of AVL Trees The height of the AVL tree is always balanced. The height never grows beyond log N, where N is the total number of nodes in the tree. It gives better search time complexity when compared to simple Binary Search trees. AVL trees have self-balancing capabilities.