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This is 11th part of java binary tree tutorial.
Java Binary tree tutorial:
- Binary tree in java
- Binary tree preorder traversal
- Binary tree postorder traversal
- Binary tree inorder traversal
- Binary tree level order traversal
- Binary tree spiral order traversal
- Binary tree reverse level order traversal
- Binary tree boundary traversal
- Print leaf nodes of binary tree
- Count leaf nodes in binary tree
- get maximum element in binary tree
- Print all paths from root to leaf in binary tree
- Print vertical sum of binary tree in java
- Get level of node in binary tree in java
- Lowest common ancestor(LCA) in binary tree in java
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:
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// 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:
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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; } } |
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Node data: 70,Level :3 Node data: 100,Level :0 Node data: 60,Level :2 Node data: 40,Level :1 |
Java Binary tree tutorial:
- Binary tree in java
- Binary tree preorder traversal
- Binary tree postorder traversal
- Binary tree inorder traversal
- Binary tree level order traversal
- Binary tree spiral order traversal
- Binary tree reverse level order traversal
- Binary tree boundary traversal
- Print leaf nodes of binary tree
- Count leaf nodes in binary tree
- get maximum element in binary tree
- Print all paths from root to leaf in binary tree
- Print vertical sum of binary tree in java
- Get level of node in binary tree in java
- Lowest common ancestor(LCA) in binary tree in java
Please go through Interview programs in java for more such programs.
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Hi,
Following your blog and its pretty good and clear. Thanks for building this up.