inversion on Binary Tree
Last updated: August 18, 2025
Quick Overview
Given a binary tree, write a function to invert the tree by swapping the left and right children of all nodes. The function should take the root node of the binary tree as input and return the root of the inverted binary tree.
Scale AI
August 18, 20252
14
2,923 solved
Given a binary tree, write a function to invert the tree by swapping the left and right children of all nodes. The function should take the root node of the binary tree as input and return the root of the inverted binary tree.
Coding interviews at Scale AI focus on problem-solving approach as much as the final solution. The interviewer wants to see you break down the problem, consider edge cases, and optimize iteratively. Communication throughout the process is key.
What the Interviewer Expects
- Recognize the underlying problem pattern (sliding window, two pointers, BFS/DFS, etc.)
- Discuss multiple approaches and trade-offs before coding
- Implement an optimal solution with clean, production-quality code
- Handle all edge cases including boundary conditions and invalid input
- Optimize both time and space complexity with clear justification
- Test your solution systematically with well-chosen examples
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would you test this solution thoroughly?
- How would you modify your solution to handle streaming input?
- What happens if the input contains duplicates?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to invert a binary tree by swapping the left and right children of all nodes. This is a classic example of a tree traversal problem where we can utilize Depth-First Search (DFS...
Approach
- Base Case: If the current node is null, return null. This handles the scenario where we've reached the end of a branch.
- Swap Children: For the current node, swap its left and right child...
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