Insertion in a Binary Tree (Level Order) in Java

March 22, 2023

Insertion in Binary Tree

Insertion in Binary Tree is being discussed in this article. A binary tree can be defined as a finite set of elements, which can either be empty or have at most two children. Given a tree and a key, add a node in the first available node in the tree. After adding the node, print the level order traversal.

Binary Tree

A Binary Tree is a data structure with maximum of two children for each parent.
Level Order Traversal is an example Of Breadth First Search algorithm.
Level order is a traversal in which each node is visited in the level before we move to a lower level.
Queues are used to find the level order traversal.

Searching in a Binary Search Tree

AVL Tree Insertion

Depth First Traversals

Level Order Traversal

Construct Tree from given Inorder and Preorder traversals

Algorithm

Iterate level order traversal of the given tree using queue.
If we find a node whose left child is empty, we make new key as left child of the node.
Else if we find a node whose right child is empty, we make the new key as right child.
Keep traversing the tree until we find a node whose wither left or right child is empty.

Run

import java.util.*;
class Node
{
  int value;
  Node left, right;


    Node (int value)
  {
    this.value = value;
    left = right = null;
  }
}

class Main
{
  static Node root;
  //static Node temp=root;
  public static void inorder (Node ptr)
  {
    if (ptr == null)
      return;
    inorder (ptr.left);

    System.out.print (ptr.value + " ");
    inorder (ptr.right);
  }

  public static void insert (Node ptr, int item)
  {
    if (ptr == null)
      {
	root = new Node (item);
	return;
      }
    Queue < Node > que = new LinkedList < Node > ();
    que.add (ptr);

    while (!que.isEmpty ())
      {
	ptr = que.peek ();
	que.remove ();
	if (ptr.left == null)
	  {
	    ptr.left = new Node (item);
	    break;
	  }
	else
	  que.add (ptr.left);

	if (ptr.right == null)
	  {
	    ptr.right = new Node (item);
	    break;
	  }
	else
	  que.add (ptr.right);
      }
  }


  public static void main (String[]args)
  {
    Node root = new Node (10);
    root.left = new Node (20);
    root.left.left = new Node (30);
    root.right = new Node (40);
    root.right.left = new Node (50);
    root.right.right = new Node (60);

    System.out.println ("Inorder Traversal before Insertion: ");
    inorder (root);

    int item = 7;
    insert (root, item);

    System.out.println ("\nInorder Traversal after insertion");

    inorder (root);
  }
}

Output:

Inorder Traversal before Insertion: 
30 20 10 50 40 60 
Inorder Traversal after insertion
30 20 70 10 50 40 60

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Introduction to Trees

Binary Trees

Binary Tree in Data Structures (Introduction)
Tree Traversals: Inorder Postorder Preorder : C | C++ | Java
Inorder Postorder PreOrder Traversals Examples
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- Preorder Tree Traversal in Binary Tree : C | C++ | Java
- Postorder Tree Traversal in Binary Tree : C | C++ | Java
Tree Traversal without Recursion
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- Preorder Tree Traversal without Recursion – C | C++ | Java
- Postorder Tree Traversal without Recursion – C | C++ | Java

Binary Search Trees

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- BST: Insertion in a Binary Search Tree : C | C++ | Java
- BST: Deletion in a Binary Search Tree : C | C++ | Java

Traversals

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Tree Traversals: Depth First Search (DFS) : C | C++ | Java
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B – Trees

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- B-Tree: Introduction
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AVL Trees

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- AVL Tree Deletion : C | C++ | Java
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- Searching in Binary Tree – C | C++ | Java
- Searching in a Binary Search Tree – C | C++ | Java

Complete Programs for Trees

Depth First Traversals – C | C++ | Java
Level Order Traversal – C | C++ | Java
Construct Tree from given Inorder and Preorder traversals – C | C++ | Java
Construct Tree from given Postorder and Inorder traversals – C | C++ | Java
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Level Order Traversal LIne by Line – C | C++| Java
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check whether tree is Symmetric C| C++| Java.
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