Binary Tree Traversal

Binary trees are fundamental data structures in computer science and understanding their traversal is crucial for various applications. Traversing a binary tree means visiting all the nodes in a specific order. There are several traversal methods, each with its unique applications and benefits. This article will explore the main types of binary tree traversal: in-order, pre-order, post-order, and level-order.

A binary tree is a hierarchical data structure where each node has at most two child nodes: a left child and a right child. Traversal involves systematically visiting each node in the tree, ensuring that every node is accessed exactly once. This process is very important for various operations like printing the tree’s contents, searching for specific elements, and evaluating expressions represented by the tree.

1. Pre-order Traversal
2. In-order Traversal
3. Post-order Traversal
4. Level-order Traversal

In in-order traversal, the left child is visited first, followed by the node itself, and then the right child. This can be visualized as Left – Root – Right.

Below are some important concepts in In-order Traversal:

• Inorder Tree Traversal without Recursion
• Inorder Tree Traversal without recursion and without stack!
• Find all possible binary trees with given Inorder Traversal
• Replace each node in binary tree with the sum of its inorder predecessor and successor
• Populate Inorder Successor for all nodes
• Inorder Successor of a node in Binary Tree
• Find n-th node of inorder traversal

In pre-order traversal, the node is visited first, followed by its left child and then its right child. This can be visualized as Root – Left – Right.

Below are some important concepts in Pre-Order Traversal:

• Morris traversal for Preorder
• Iterative Preorder Traversal
• Calculate depth of a full Binary tree from Preorder
• Number of Binary Trees for given Preorder Sequence length
• Modify a binary tree to get Preorder traversal using right pointers only

In post-order traversal, the left child is visited first, then the right child, and finally the node itself. This can be visualized as Left – Right – Root.

Below are some important concepts in Post-Order Traversal:

• Print Postorder traversal from given Inorder and Preorder traversals
• Iterative Postorder Traversal | Set 1 (Using Two Stacks)
• Iterative Postorder Traversal | Set 2 (Using One Stack)
• Postorder traversal of Binary Tree without recursion and without stack

In level-order traversal, the nodes are visited level by level, starting from the root node and then moving to the next level. This can be visualized as Level 1 – Level 2 – Level 3 – ….

Below are some important concepts in Level-Order Traversal:

• Level Order Tree Traversal
• Level order traversal in spiral form
• Level order traversal line by line
• Level order traversal with direction change after every two levels
• Reverse Level Order Traversal
• Perfect Binary Tree Specific Level Order Traversal
• Perfect Binary Tree Specific Level Order Traversal | Set 2

• Reverse tree path
• Reverse alternate levels of a perfect binary tree
• Diagonal Traversal of Binary Tree
• Iterative diagonal traversal of binary tree
• Boundary Traversal of binary tree
• Density of Binary Tree in One Traversal

All articles on Binary Tree !

Quick Links :

• ‘Practice Problems’ on Trees
• ‘Quizzes’ on Binary Trees