Design a max-stack with efficient operations
Company: LinkedIn
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Onsite
Design a stack that supports push
(x), pop(), top(), peekMax(), and popMax(). The popMax operation must remove and return the maximum element; if there are multiple maximums, remove the most recently pushed one. Implement two approaches:
(A) an amortized O(
1) solution using auxiliary structures, and
(B) an O(log n) popMax solution using a balanced tree or heap plus linked nodes. Explain how you will handle duplicates, empty-structure edge cases, and concurrency concerns for a high-throughput system. Provide time/space complexities and brief test cases.
Overview: This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Design a max-stack with efficient operations states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.