Binary Tree Level Order Traversal in Java

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1. Introduction

This article provides a detailed exploration of the Level Order traversal technique in binary trees, focusing on its implementation in Java.

2. What is Level Order Traversal?

Level Order traversal involves visiting all nodes at same level before moving to next level. This means traversing binary tree level by level.

Level order traversal of below binary tree will be:

We will use Queue for Level Order traversal. This algorithm is very similar to Breadth first search of graph.

3. Process of Level Order Traversal

  • Create empty queue and pust root node to it.
  • Do the following when queue is not empty
    • Pop a node from queue and print it
    • Push left child of popped node to queue if not null
    • Push right child of popped node to queue if not null

4. Complete Java Program

Lets say our binary tree is :

So Level Order traversal will work as below:

Here is java program for level order traversal:

Run above program and you will get following output:

Level Order traversal of binary tree will be:
40 20 60 10 30 50 70

5. Complexity of Algorithm

The time complexity of Level Order traversal is o(n) where n is number of nodes in binary tree. This is because each node is visited exactly once during level order traversal.

The space complexity of Level Order traversal is o(w) where w is maximum width in binary tree. This is because maximum number of nodes in the queue is proportional to the width of binary tree at any point in time.

6. Conclusion

In this article, we covered about Binary tree Level Order traversal and its implementation. We have done traversal using similar to breadth first search. We also discussed about time and space complexity for the traversal.


Java Binary tree tutorial

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Comments

  1. You have a typo after explain how Level Order traversal works on “Lets create java program for PreOrder traversal:” it is not PreOrder, anyway everything is well explained and is easy to see that is a typo.

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