This is 7th part of java binary tree tutorial.
In this post, we will see about program to print leaf nodes in a binary tree in java
Algorithm-
Steps for counting number of leaf nodes are:
- If node is null then return 0
- If encounterd leaf node(i.e. node.left is null and node.right is null) then print the node.
- Recursively visit leaf subtree and right subtree.
Code for recursion will be:
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// Recursive Solution // print leaf nodes public static void printLeafNodes(TreeNode node) { if(node==null) return; if(node.left == null && node.right == null) { System.out.printf("%d ",node.data); } printLeafNodes(node.left); printLeafNodes(node.right); } |
Example:
Binary tree:
Lets create java program for counting number of leaf nodes:
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package org.arpit.java2blog.binarytree; public class BinaryTreePrintLeafNodes { public static class TreeNode { int data; TreeNode left; TreeNode right; TreeNode(int data) { this.data=data; } } // Recursive Solution // print leaf nodes public static void printLeafNodes(TreeNode node) { if(node==null) return; if(node.left == null && node.right == null) { System.out.printf("%d ",node.data); } printLeafNodes(node.left); printLeafNodes(node.right); } public static void main(String[] args) { // Creating a binary tree TreeNode rootNode=createBinaryTree(); System.out.println("Printing leaf nodes in binary tree :"); printLeafNodes(rootNode); } 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); TreeNode node5=new TreeNode(5); TreeNode node55=new TreeNode(55); rootNode.left=node20; rootNode.right=node60; node20.left=node10; node20.right=node30; node60.left=node50; node60.right=node70; node10.left=node5; node50.right=node55; return rootNode; } } |
Run above program and you will get following output:
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Printing leaf nodes in binary tree : 5 30 55 70 |
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
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