Get level of a node in binary tree in java

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Java Binary tree tutorial:
- Algorithm :
Java Binary tree tutorial:
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This is 11th part of java binary tree tutorial.

Java Binary tree tutorial:

In this post, we will see about program to get level of node in a binary tree in java.

We will search for a key in binary tree. Root will be at level 1. If we do not find key in binary tree then its level will be 0.

Algorithm :

Steps for getting level of a node in binary tree:

If node is null then return 0
If node’s data is equal to key, then return level.
Recursively search key in left subtree
If not found, then search in right subtree

Code for recursion will be:

// Recursive Solution

//To get level of node in a binary tree

public static int getLevelOfNode(TreeNode root,int key,int level)

{

if(root==null)

return 0;

if(root.data==key)

return level;

int result=getLevelOfNode(root.left,key,level+1) ;

if(result!=0)

{

// If found in left subtree , return

return result;

}

result= getLevelOfNode(root.right,key,level+1);

return result;

}

Lets create java program to get level of node in binary tree:

Lets say, your binary tree is this:

package org.arpit.java2blog.binarytree;

public class BinaryTreeGetLevelNode {

public static class TreeNode

{

int data;

TreeNode left;

TreeNode right;

TreeNode(int data)

{

this.data=data;

}

// Recursive Solution

//To get level of node in a binary tree

public static int getLevelOfNode(TreeNode root,int key,int level)

{

if(root==null)

return 0;

if(root.data==key)

return level;

int result=getLevelOfNode(root.left,key,level+1) ;

if(result!=0)

{

// If found in left subtree , return

return result;

}

result= getLevelOfNode(root.right,key,level+1);

return result;

}

public static void main(String[] args)

{

// Creating a binary tree

TreeNode rootNode=createBinaryTree();

System.out.println("Node data: 70,Level :"+getLevelOfNode(rootNode, 70, 1));

System.out.println("Node data: 100,Level :"+getLevelOfNode(rootNode, 100, 1));

System.out.println("Node data: 60,Level :"+getLevelOfNode(rootNode, 60, 1));

System.out.println("Node data: 40,Level :"+getLevelOfNode(rootNode, 40, 1));

}

public static TreeNode createBinaryTree()

{

TreeNode rootNode =new TreeNode(40);

TreeNode node20=new TreeNode(20);

TreeNode node10=new TreeNode(10);

TreeNode node30=new TreeNode(30);

TreeNode node60=new TreeNode(60);

TreeNode node50=new TreeNode(50);

TreeNode node70=new TreeNode(70);

rootNode.left=node20;

rootNode.right=node60;

node20.left=node10;

node20.right=node30;

node60.left=node50;

node60.right=node70;

return rootNode;

}

Run above program and you will get following output:

Node data: 70,Level :3

Node data: 100,Level :0

Node data: 60,Level :2

Node data: 40,Level :1

Java Binary tree tutorial:

Please go through Interview programs in java for more such programs.

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Get level of a node in binary tree in java