Implement Deque with in-place
Last updated: September 25, 2025
Quick Overview
Implement a Hash Map data structure that supports insert, delete, and lookup operations in O(1) time.
Scale AI
September 25, 202537
15
3,248 solved
Implement a Hash Map data structure that supports insert, delete, and lookup operations in O(1) time.
This coding problem is frequently asked during Phone Screen at Scale AI. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Scale AI 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
- Can you solve this iteratively instead of recursively (or vice versa)?
- Can you solve this in a single pass?
- How would you test this solution thoroughly?
- How would your solution change if the input was sorted?
Sharpen Your Skills on Codemia
Practice similar problems with our interactive workspace, get AI feedback, and track your progress.
Practice DSA ProblemsSample Answer
Problem Analysis
Start by understanding the input/output format and constraints. Identify the core problem pattern. Ask clarifying questions: Is the input sorted? Can ...
Brute Force Approach
Always start with the simplest correct solution, even if it's not optimal. This shows you can solve the problem and gives you a baseline to optimize f...
Submit Your Answer
