// Iterative Queue based C# program  

// to do level order traversal 

// of Binary Tree 

using System; 

using System.Collections.Generic; 

/* Class to represent Tree node */

public class Node  

{ 

    public int data; 

    public Node left, right; 

    public Node(int item)  

    { 

        data = item; 

        left = null; 

        right = null; 

    } 

} 

/* Class to print Level Order Traversal */

public 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 Queue<Node>(); 

        queue.Enqueue(root); 

        while (queue.Count != 0)  

        { 

            /* poll() removes the present head. 

            For more information on poll() visit  

            http://www.tutorialspoint.com/java/util/linkedlist_poll.htm */

            Node tempNode = queue.Dequeue(); 

            Console.Write(tempNode.data + " "); 

            /*Enqueue left child */

            if (tempNode.left != null)  

            { 

                queue.Enqueue(tempNode.left); 

            } 

            /*Enqueue right child */

            if (tempNode.right != null)  

            { 

                queue.Enqueue(tempNode.right); 

            } 

        } 

    } 

    // Driver code 

    public static void Main()  

    { 

        /* 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); 

        Console.WriteLine("Level order traversal " + 

                            "of binary tree is - "); 

        tree_level.printLevelOrder(); 

    } 

} 

/* This code contributed by PrinciRaj1992 */

​

/*Output:

Level order traversal of binary tree is - 

1 2 3 4 5 */