Optimize rotation for with follow-up
Last updated: September 29, 2025
Quick Overview
Given an array of integers, rotate the array to the right by a specified number of steps, ensuring that the rotation is performed in-place. The function should take the array and the number of steps as input and return the modified array. For example, rotating the array [1, 2, 3, 4, 5] by 2 steps should result in [4, 5, 1, 2, 3].
Slack
September 29, 2025553
7
4,336 solved
Given an array of integers, rotate the array to the right by a specified number of steps, ensuring that the rotation is performed in-place. The function should take the array and the number of steps as input and return the modified array. For example, rotating the array [1, 2, 3, 4, 5] by 2 steps should result in [4, 5, 1, 2, 3].
Slack uses this problem in the Onsite to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.
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
- Can you optimize the space complexity of your solution?
- What if the input doesn't fit in memory?
- How would you test this solution thoroughly?
- How would you parallelize this solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to rotate an array to the right by a specified number of steps. This can be recognized as a problem that can effectively utilize the reverse technique. The main pattern her...
Approach
To rotate the array by k steps, we can break down the problem into the following steps:
- Normalize
kby takingk % nwherenis the length of the array. This accounts for cases wherekis ...
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