Implement Deque with without recursion
Last updated: September 26, 2025
Quick Overview
Implement a Deque (double-ended queue) data structure that supports the following operations: addFirst, addLast, removeFirst, removeLast, getFirst, and getLast. Your implementation should not use recursion and must handle edge cases such as operations on an empty deque. Ensure that all operations are efficient and adhere to the expected time complexity of O(1) for each operation.
Tesla
September 26, 2025105
11
1,723 solved
Implement a Deque (double-ended queue) data structure that supports the following operations: addFirst, addLast, removeFirst, removeLast, getFirst, and getLast. Your implementation should not use recursion and must handle edge cases such as operations on an empty deque. Ensure that all operations are efficient and adhere to the expected time complexity of O(1) for each operation.
Tesla 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
- What if the input doesn't fit in memory?
- How would your solution change if the input was sorted?
- What is the worst-case input for your solution?
- Can you solve this iteratively instead of recursively (or vice versa)?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires implementing a Deque (double-ended queue) that supports operations on both ends efficiently. The key pattern here is to use a doubly linked list to allow O(1) time complexity ...
Approach
- Node Structure: Create a
Nodeclass to represent each element in the deque. Each node will have a value and pointers to the next and previous nodes. - Deque Class: Create a
Dequeclas...
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