PreOrder traversal of binary tree implementation in Java

By | July 15, 2020

This post talks about PreOrder traversal of binary tree implementation in Java

This is the simplest traversal. In this traversal each node is processed before the subtrees, it still requires that some information must be maintained while moving down the tree. in the below picture, 1 then the left subtree, and this is followed by the right subtree.

PreOrder traversal is defined as follows:

  • Visit the root
  • Traverse the Left Subtree
  • Traverse the Right Subtree

Binary Tree For Traversal

PreOrder, traversal can be implemented either recursive and iterative approach. Both Approaches have shown below:

Recursive Approach:

Time Complexity: O(n) and Space Complexity: O(n)

Iterative Approach:

In the Iterative approach, A stack is required as we need to remember the current node so that after completing the left subtree. we can go to the right subtree. We have to simulate the same, first, we process the current node and before going to the left subtree. we store the current node on the stack. After completing the left subtree processing, pop the element and go to the right subtree. We have to continue this process until the stack is non-empty.

Time Complexity: O(n) and Space Complexity: O(n)

Below is the Complete Source code: 

PreOrder Processing In BinaryTree

BinaryTree.java

 

ClientTest.java

The output of This Program:

…..Binary Tree PreOrder Processing output using Recursive method….
1 2 4 5 3 6 7
…..Binary Tree PreOrder Processing output using Iterative method….
1 2 4 5 3 6 7

You May Also Like:

Introduction to Tree Data Structure
Introduction to Binary Tree
Structure of Binary Trees
Operations and use of Binary Trees
Binary Tree Traversals

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