Symmetric Tree - Mirror Image

 


Given the root of a binary tree, check whether it is a mirror of itself (i.e., symmetric around its center).


 


Example 1:



Input: root = [1,2,2,3,4,4,3]

Output: true

Example 2:



Input: root = [1,2,2,null,3,null,3]

Output: false

 


Constraints:


The number of nodes in the tree is in the range [1, 1000].

-100 <= Node.val <= 100

 

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public boolean isSymmetric(TreeNode root) {
       
        if(root ==null) return true;
       
        return isMirror(root.left, root.right);

    }

    public static boolean isMirror(TreeNode root1,TreeNode root2){

        if(root1 ==null && root2==null) return true;

        if(root1 ==null || root2==null) return false;

        return (root1.val == root2.val) && isMirror(root1.left,root2.right) &&
        isMirror(root1.right,root2.left);

    }


}

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