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Program: Write a program to find given two trees are mirror or not.


Write a simple program to identify given two binary trees are mirrored image of each other. Here is an example image of mirrored trees:

Binary tree mirror image

Here are the steps to find out mirrored binary trees:

  1. If both given trees root node values are same.
  2. Left subtree of root of first tree is mirror of right subtree of root of second tree.
  3. Right subtree of root of first tree is mirror of left subtree of root of second tree.
package com.java2novice.ds.trees;

public class MirrorTreesEx {

	public static boolean areMirrorTrees(Node a_root, Node b_root) {
		 * Recursion exist condition - 1
		 * When both nodes are null, return true
		if(a_root == null && b_root == null) {
			return true;
		 * Recursion exist condition - 2
		 * When one of the node is null, return false
		if(a_root == null || b_root == null) {
			return false;
		return == &&
				areMirrorTrees(a_root.left, b_root.right) &&
				areMirrorTrees(a_root.right, b_root.left);
	public static void main(String arg[]) {
		BinaryTree a = new BinaryTree();
		a.root = new Node(5);
		a.root.left = new Node(6);
		a.root.right = new Node(7);
		a.root.left.left = new Node(8);
		a.root.left.right = new Node(9);
		BinaryTree b = new BinaryTree();
		b.root = new Node(5);
		b.root.left = new Node(7);
		b.root.right = new Node(6);
		b.root.right.left = new Node(9);
		b.root.right.right = new Node(8);
		System.out.println("Is Mirror Trees? "+MirrorTreesEx.areMirrorTrees(a.root, b.root));
		BinaryTree a1 = new BinaryTree();
		a1.root = new Node(5);
		a1.root.left = new Node(6);
		a1.root.right = new Node(7);
		a1.root.left.left = new Node(8);
		a1.root.left.right = new Node(9);
		BinaryTree b1 = new BinaryTree();
		b1.root = new Node(5);
		b1.root.left = new Node(7);
		b1.root.right = new Node(6);
		b1.root.right.left = new Node(9);
		System.out.println("Is Mirror Trees? "+MirrorTreesEx.areMirrorTrees(a1.root, b1.root));

Is Mirror Trees? true
Is Mirror Trees? false
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List Of All Interview Programs:

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  34. Write a program to implement hashcode and equals.
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Knowledge Centre
What is abstract class or abstract method?
We cannot create instance for an abstract class. We can able to create instance for its subclass only. By specifying abstract keyword just before class, we can make a class as abstract class.

public abstract class MyAbstractClass{


Abstract class may or may not contains abstract methods. Abstract method is just method signature, it does not containes any implementation. Its subclass must provide implementation for abstract methods. Abstract methods are looks like as given below:

public abstract int getLength();
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I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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