Java Day 23: BST Level-Order Traversal

A level-order traversal, also known as a breadth-first search, visits each level of a tree's nodes from left to right, top to bottom. You are given a pointer, root , pointing to the root of a binary search tree. Complete the levelOrder function provided in your editor so that it prints the level-order traversal of the binary search tree.

Hint: You'll find a queue helpful in completing this challenge.



  1. import java.io.*;

  2. import java.util.*;

  3. class Node{

  4.     Node left,right;

  5.     int data;

  6.     Node(int data){

  7.         this.data=data;

  8.         left=right=null;

  9.     }

  10. }

  11. class Solution{

  12. 

  13. 	public static void levelOrder(Node root) {

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

  15.         queue.add(root);

  16. 

  17.         while (!queue.isEmpty()) {

  18.             Node curr = queue.remove();

  19.             System.out.print(curr.data + " ");

  20. 

  21.             if (curr.left != null) queue.add(curr.left);

  22.             if (curr.right != null) queue.add(curr.right);

  23.         }

  24.     }

  25. 

  26. 	public static Node insert(Node root,int data){

  27.         if(root==null){

  28.             return new Node(data);

  29.         }

  30.         else{

  31.             Node cur;

  32.             if(data<=root.data){

  33.                 cur=insert(root.left,data);

  34.                 root.left=cur;

  35.             }

  36.             else{

  37.                 cur=insert(root.right,data);

  38.                 root.right=cur;

  39.             }

  40.             return root;

  41.         }

  42.     }

  43.     public static void main(String args[]){

  44.             Scanner sc=new Scanner(System.in);

  45.             int T=sc.nextInt();

  46.             Node root=null;

  47.             while(T-->0){

  48.                 int data=sc.nextInt();

  49.                 root=insert(root,data);

  50.             }

  51.             levelOrder(root);

  52.         }	

  53. }
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