rotation on Binary Tree
Last updated: September 1, 2025
Quick Overview
Given a binary tree, implement a function to rotate the tree to the right by a specified number of levels. The function should take the root of the binary tree and an integer representing the number of levels to rotate as input, and return the new root of the rotated binary tree.
Amazon
September 1, 202543
15
3,205 solved
Given a binary tree, implement a function to rotate the tree to the right by a specified number of levels. The function should take the root of the binary tree and an integer representing the number of levels to rotate as input, and return the new root of the rotated binary tree.
This coding problem is frequently asked during Phone Screen at Amazon. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Amazon expects candidates to write production-quality code, not just solve the puzzle.
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 is the worst-case input for your solution?
- How would your solution change if the input was sorted?
- How would you modify your solution to handle streaming input?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem involves rotating a binary tree to the right by a specified number of levels. The key pattern here is to use tree traversal techniques, specifically Depth-First Search (DFS). This is becau...
Approach
- Count the Levels: First, we need to determine the height of the binary tree to handle rotations that exceed the height. This is done using a recursive DFS approach. For instance, if the tree ha...
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