Implement Stack with O(n) time
Last updated: February 10, 2026
Quick Overview
Implement a stack data structure that supports push, pop, and peek operations, ensuring that all operations run in O(n) time complexity. Your implementation should allow for dynamic resizing and should handle edge cases such as popping from an empty stack. Provide a way to test your stack with a series of operations and verify the expected output for each operation.
Coinbase
February 10, 2026137
3
1,253 solved
Implement a stack data structure that supports push, pop, and peek operations, ensuring that all operations run in O(n) time complexity. Your implementation should allow for dynamic resizing and should handle edge cases such as popping from an empty stack. Provide a way to test your stack with a series of operations and verify the expected output for each operation.
Coinbase 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
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
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 optimize the space complexity of your solution?
- What is the worst-case input for your solution?
- How would your solution change if the input was sorted?
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Problem Analysis
The problem requires implementing a stack data structure with push, pop, and peek operations, specifically ensuring that all operations run in O(n) time complexity. To achieve this, we can leverage a ...
Approach
- Initialization: Create a class
DynamicStackthat maintains a list to store stack elements and an integer to track the current size. - Push Operation: When pushing, check if the current s...
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