Lecture 275:- Binary Tree Traversals

Binary tree traversal refers to the process of systematically visiting or traversing all the nodes of a binary tree in a specific order. There are three commonly used types of binary tree traversals:

1. Inorder Traversal:
   • In an inorder traversal, we visit the left subtree, then the root node, and finally the right subtree.
   • The order of visiting nodes in an inorder traversal is: Left, Root, Right.
   • In a binary search tree (BST), the nodes are visited in ascending order when performing an inorder traversal.
2. Preorder Traversal:
   • In a preorder traversal, we visit the root node first, then the left subtree, and finally the right subtree.
   • The order of visiting nodes in a preorder traversal is: Root, Left, Right.
   • Preorder traversal is useful for creating a copy of the tree or for expressions in prefix notation.
3. Postorder Traversal:
   • In a postorder traversal, we visit the left subtree first, then the right subtree, and finally the root node.
   • The order of visiting nodes in a postorder traversal is: Left, Right, Root.
   • Postorder traversal is useful for deleting nodes or for expressions in postfix notation.

Here's an example binary tree to illustrate the traversals:

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        1       / \      2   3     / \    4   5

Inorder Traversal: 4, 2, 5, 1, 3 Preorder Traversal: 1, 2, 4, 5, 3 Postorder Traversal: 4, 5, 2, 3, 1

Each traversal order yields a different sequence of nodes visited, providing different ways to examine and process the elements in the binary tree. Binary tree traversals are widely used in algorithms for various applications such as searching, sorting, expression evaluation, and tree manipulation.