inversion on Binary Tree
Last updated: July 11, 2025
Quick Overview
Given a binary tree, write a function to invert the tree, 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.
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July 11, 2025148
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Given a binary tree, write a function to invert the tree, 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 Zoom 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
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
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 your solution change if the input was sorted?
- How would you parallelize this solution?
- What is the worst-case input for your solution?
- Can you solve this iteratively instead of recursively (or vice versa)?
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Problem Analysis
To invert a binary tree, we need to swap the left and right children of every node in the tree. This problem can be approached using a recursive method, which fits the nature of tree structures where ...
Approach
- Start at the root of the binary tree.
- If the current node is null, return null (base case).
- Swap the left and right children of the current node.
- Recursively call the invert function...
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