Invert Binary Tree
Description
Given the root of a binary tree, invert the tree and return its root.
To invert a binary tree, swap the left and right children of every node.
For example:
4
/ \
2 7
/ \ / \
1 3 6 9
becomes:
4
/ \
7 2
/ \ / \
9 6 3 1
Example 1
Input
root = [4,2,7,1,3,6,9]
Output
[4,7,2,9,6,3,1]
Explanation
The left and right children of every node are swapped.
Example 2
Input
root = [2,1,3]
Output
[2,3,1]
Explanation
The left child 1 and right child 3 of the root are swapped.
Constraints
Hints:
Hint 1
For every node, swap its left and right children.
Hint 2
After swapping the children of the current node, recursively invert both subtrees.
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