# What Is Called Tree in Data Structure?

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Heather Bennett

What Is Called Tree in Data Structure?

A tree is a widely used data structure in computer science that represents hierarchical relationships between elements. It is composed of nodes connected by edges, with a single node known as the root serving as the starting point for traversing the tree.

## Tree Terminology

Before diving deeper into trees, let’s familiarize ourselves with some key terminology:

• Node: Each element in a tree is called a node. Nodes can contain data and have connections to other nodes.
• Edge: The connection between nodes is known as an edge.

It represents the relationship or link between two nodes.

• Root: The topmost node of a tree is called the root. It serves as the starting point for traversing the tree.
• Parent: A node that has one or more child nodes is referred to as a parent node.
• Child: Nodes directly connected to a parent node are called its child nodes.
• Sibling: Nodes that share the same parent are known as sibling nodes.

## The Tree Structure

A tree structure consists of levels and branches. Each level contains nodes, and branches represent connections between these nodes. The hierarchy of levels determines how elements are organized within the tree.

The first level, which contains only the root node, is referred to as level 0. Nodes directly connected to the root form level 1, their children form level 2, and so on.

### Types of Trees

There are various types of trees, each with its own characteristics and applications. Some common types include:

• Binary Tree: A binary tree is a tree in which each node has at most two children, known as the left child and the right child.
• Binary Search Tree (BST): A binary search tree is a binary tree that follows a specific ordering property. For any given node, all nodes in its left subtree have values less than the node’s value, and all nodes in its right subtree have values greater than the node’s value.
• Balanced Tree: A balanced tree is a type of tree where the difference in height between the left and right subtrees of any node is limited.

This ensures efficient searching, insertion, and deletion operations.

• B-tree: A B-tree is a self-balancing search tree commonly used in databases and file systems. It allows efficient access to large amounts of data stored on disk.

## Tree Traversal

Tree traversal refers to visiting each node in a tree exactly once. There are several ways to traverse a tree:

• Inorder Traversal: In an inorder traversal, nodes are visited in ascending order (for binary search trees).
• Preorder Traversal: In a preorder traversal, the root node is visited first, followed by its left subtree and then its right subtree.
• Postorder Traversal: In a postorder traversal, the root node is visited after its children have been visited.
• Level Order Traversal: In a level order traversal, nodes are visited level by level, starting from the root.

## Applications of Trees

Trees have various applications in computer science and beyond. Some common use cases are:

• File Systems: File systems often use tree structures to organize directories and files.
• Hierarchical Data Representation: Trees provide an intuitive way to represent hierarchical relationships, such as organization charts or family trees.
• Database Indexing: B-trees are commonly used for indexing large amounts of data in databases.
• Artificial Intelligence: Decision trees are employed in machine learning algorithms for classification and regression tasks.

In conclusion, a tree is a fundamental data structure that represents hierarchical relationships between elements. Understanding trees and their various types, traversal methods, and applications is crucial for efficient problem-solving in computer science.