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.
Quick Answer: This question evaluates a candidate's ability to design and analyze a data structure that supports stack operations with efficient maximum retrieval and removal, testing algorithmic design, complexity analysis, and handling of edge cases such as duplicates and empty-structure behavior.