LeetCode 226: Invert Binary Tree — Step-by-Step Visual Trace

Easy — Binary Tree | Recursion | Depth-First Search | Tree Traversal

The Problem

Given the root of a binary tree, invert the tree by swapping the left and right children of every node, and return the root of the inverted tree.

Approach

Use a recursive depth-first approach to traverse the tree. At each node, swap the left and right children, then recursively invert both subtrees. The base case returns None for null nodes.

Time: O(n) · Space: O(h)

Code

class Solution:
    def invertTree(self, root: TreeNode) -> TreeNode:
        if not root:
            return None

        # Swap left and right subtrees
        root.left, root.right = root.right, root.left

        # Recursively invert left and right subtrees
        self.invertTree(root.left)
        self.invertTree(root.right)

        return root

Watch It Run

Try it yourself: Open TraceLit and step through every line.

Built with TraceLit — the visual algorithm tracer for LeetCode practice.

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