Implement Deque with O(n) time
Last updated: August 31, 2025
Quick Overview
Implement a deque (double-ended queue) data structure that supports the operations of adding and removing elements from both ends in O(n) time. Your implementation should include methods for pushFront, pushBack, popFront, popBack, and peek, with appropriate input and output specifications for each operation. Ensure that your solution handles edge cases, such as operations on an empty deque.
Snowflake
August 31, 20252
11
186 solved
Implement a deque (double-ended queue) data structure that supports the operations of adding and removing elements from both ends in O(n) time. Your implementation should include methods for pushFront, pushBack, popFront, popBack, and peek, with appropriate input and output specifications for each operation. Ensure that your solution handles edge cases, such as operations on an empty deque.
Snowflake uses this problem in the Technical Screen 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
- How would you modify your solution to handle streaming input?
- What is the worst-case input for your solution?
- What if the input doesn't fit in memory?
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
The problem requires us to implement a deque (double-ended queue) that allows adding and removing elements from both ends efficiently. Given that we need to perform operations such as pushFront, `pu...
Approach
- Data Structure: We will use a doubly linked list to hold our elements, where each node contains a value, a reference to the next node, and a reference to the previous node. This allows us to ea...
Submit Your Answer
