Symmetric Tree
Given the root of a binary tree, determine whether the tree is symmetric around its center.
A binary tree is symmetric if its left subtree is a mirror reflection of its right subtree.
Example 1
Input
root = [1,2,2,3,4,4,3]
Output
true
Explanation
The left and right subtrees are mirror images of each other.
Example 2
Input
root = [1,2,2,null,3,null,3]
Output
false
Explanation
The two subtrees have different structures, so the tree is not symmetric.
Constraints
Hints:
Hint 1
A tree is symmetric if its left and right subtrees are mirror images.
Hint 2
Compare the left child of one node with the right child of the other node.
Author & Technical Reviewer
Technically reviewed by: ExamAdda Technical Review Team
Technical Reviewers, ExamAdda
Software engineers at ExamAdda who check every article's definitions, complexity claims and code examples before and after publishing.
Published
Aug 11, 2026
Last updated
Aug 12, 2026
Content Verification Methodology
Definitions and complexity claims were checked against authoritative computer-science references. Code examples were compiled and tested with standard, boundary and edge-case inputs.
Expected Output