Write a function to find whether two binary tree are mirror image of each other or not?

Question

                    50                      50
                   /  \                    /  \
                  20     30              30   20
Sample Tree<---   /  \                       /  \   ----> Mirror image
               70      80                   80   70
              /  \    \                    /    /  \  
             10  40     60                60   40   10

Answer 1

Objective: - Given two binary trees check if they are mir­ror image of each other

Example:

Approach:

Do the pre­order tra­ver­sal on both the trees simultaneously.

if any node doesn’t have corresponding node in the another tree, return false.

check if left node in one tree is the right node in another tree, and vice verse.

Code:

public class CheckMirrorTree {

    public boolean checkMirror(Node root1, Node root2) {
        if (root1 == null && root2 == null) {
            return true;
        }
                if(root1.data !=root2.data){
                        return false;
                }

        if ((root1 == null && root2 != null)
                || (root1 != null && root2 == null)) { // if any node doesn't
            // have corresponding node in the another tree, return false
            return false;
        }
        // check if left node in one tree is the right node in another tree, and
        // vice versa
        return checkMirror(root1.left, root2.right)
                && checkMirror(root1.right, root2.left);

    }

    public static void main(String[] args) {
        Node root1 = new Node(1);
        root1.left = new Node(2);
        root1.left.right = new Node(3);
        root1.right = new Node(4);

        Node root2 = new Node(1);
        root2.right = new Node(2);
        root2.right.left = new Node(3);
        root2.left = new Node(4);

        CheckMirrorTree i = new CheckMirrorTree();
        System.out.println("Is Mirror Trees : " + i.checkMirror(root1, root2));

    }

}

class Node {
    int data;
    Node left, right;

    public Node(int data) {
        this.data = data;
    }
}