Tree-Traverse-Order-Level-Queue

import java.util.LinkedList;
import java.util.Queue;


class Node {
    int data;
    Node left, right;

    public Node(int item)
    {
        data = item;
        left = null;
        right = null;
    }
}
class LevelOrderQueue {

    Node root;

    void printLevelOrder()
    {
       Queue<Node> queue = new LinkedList<Node>();
        queue.add(root);
        while (!queue.isEmpty()) {

            Node tempNode = queue.poll();
            System.out.print(tempNode.data + " ");
            if (tempNode.left != null) {
                queue.add(tempNode.left);
            }
            if (tempNode.right != null) {
                queue.add(tempNode.right);
            }
        }
    }

    public static void main(String args[])
    {
        LevelOrderQueue tree_level = new LevelOrderQueue();
        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);

        tree_level.printLevelOrder();
    }

//Firstly we insert the root into the queue and iterate over
//the queue until the queue is empty.
//In every iteration, we will pop from the top of
// the queue and print the value at the top of the queue.
//Then, add its left and right nodes to the end of the queue
// Time Complexity: O(N) where n is the number of nodes in the binary tree.
//Space Complexity: O(N) where n is the number of nodes in the binary tree.
}