rotation on Binary Tree
Last updated: September 9, 2025
Quick Overview
Given a binary tree, implement a function to rotate the tree to the right by one position. The function should take the root node of the binary tree as input and return the new root node after the rotation. Ensure that the structure of the tree is maintained and that the output correctly reflects the rotated tree.
Twitter/X
September 9, 202543
3
2,124 solved
Given a binary tree, implement a function to rotate the tree to the right by one position. The function should take the root node of the binary tree as input and return the new root node after the rotation. Ensure that the structure of the tree is maintained and that the output correctly reflects the rotated tree.
Coding interviews at Twitter/X 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
- What if the input doesn't fit in memory?
- Can you solve this in a single pass?
- How would you modify your solution to handle streaming input?
- How would your solution change if the input was sorted?
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Practice DSA ProblemsSample Answer
Problem Analysis
To rotate a binary tree to the right by one position, we need to rearrange the pointers of the nodes to maintain the structure of the tree. The pattern that applies here is a direct manipulation of po...
Approach
- Check if the root is None: If the root is None (empty tree), return None immediately.
- Identify the new root: The new root after rotation will be the left child of the current root node. ...
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