If you want to practice data structure and algorithm programs, you can go through 100+ java coding interview questions.
This is 8th 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 count leaf nodes in a binary tree in java
Code for recursion will be:
Lets create java program for counting number of leaf nodes:
Run above program and you will get following output:
Please go through Frequently asked java interview programs for more such programs.
Algorithm-
Steps for counting number of leaf nodes are:
-
- If node is null then return 0
- If encountered leaf node(i.e. node.left is null and node.right is null) then return 1.
- Recursively calculate number of leaf nodes using
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Number of leaf nodes= number of leaf nodes in left subtree + number of leaf nodes in right sub tree |
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// Recursive Solution /* To get the count of leaf nodes in a binary tree*/ public static int getLeafCountOfBinaryTree(TreeNode node) { if(node == null) return 0; if(node.left ==null && node.right==null) return 1; else return getLeafCountOfBinaryTree(node.left)+ getLeafCountOfBinaryTree(node.right); } |
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package org.arpit.java2blog.binarytree; public class BinaryTreeLeafCount { public static class TreeNode { int data; TreeNode left; TreeNode right; TreeNode(int data) { this.data=data; } } // Recursive Solution /* To get the count of leaf nodes in a binary tree*/ public static int getLeafCountOfBinaryTree(TreeNode node) { if(node == null) return 0; if(node.left ==null && node.right==null) return 1; else return getLeafCountOfBinaryTree(node.left)+ getLeafCountOfBinaryTree(node.right); } public static void main(String[] args) { // Creating a binary tree TreeNode rootNode=createBinaryTree(); System.out.println("Number of leaf nodes in binary tree :"+getLeafCountOfBinaryTree(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); rootNode.left=node20; rootNode.right=node60; node20.left=node10; node20.right=node30; node60.left=node50; node60.right=node70; return rootNode; } } |
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Number of leaf nodes in binary tree :4 |
