Level order traversal Java

PROGRAM FOR LEVEL ORDER TREE TRAVERSAL

import java.util.Queue;

import java.util.LinkedList;

 

/* Class to represent Tree node */

class Node {

    int data;

    Node left, right;

 

    public Node(int item) {

        data = item;

        left = null;

        right = null;

    }

}

 

/* Class to print Level Order Traversal */

class BinaryTree {

 

    Node root;

 

    /* Given a binary tree. Print

     its nodes in level order

     using array for implementing queue  */

    void printLevelOrder()

    {

        Queue<Node> queue = new LinkedList<Node>();

        queue.add(root);

        while (!queue.isEmpty())

        {

 

            /* poll() removes the present head.

            For more information on poll() visit

            http://www.tutorialspoint.com/java/

            util/linkedlist_poll.htm */

            Node tempNode = queue.poll();

            System.out.print(tempNode.data + " ");

 

            /*Enqueue left child */

            if (tempNode.left != null) {

                queue.add(tempNode.left);

            }

 

            /*Enqueue right child */

            if (tempNode.right != null) {

                queue.add(tempNode.right);

            }

        }

    }

 

    public static void main(String args[])

    {

        /* creating a binary tree and entering

         the nodes */

        BinaryTree tree_level = new BinaryTree();

        tree_level.root = new Node(1);

        tree_level.root.left = new Node(2);

        tree_level.root.right = new Node(3);

        tree_level.root.left.left = new Node(4);

        tree_level.root.left.right = new Node(5);

 

        System.out.println("Level order traversal

                            of binary tree is - ");

        tree_level.printLevelOrder();

    }

}




OUTPUT:

Level Order traversal of binary tree is 
1 2 3 4 5 

CREDITS: https://www.geeksforgeeks.org/level-order-tree-traversal/