The get/put interface sounds simple enough but the O(1) requirement is what actually matters here.
Start by clarifying the requirements and constraints, then propose a hash map combined with a doubly linked list to achieve O(1) operations. Walk through the design, implement the core methods, and discuss trade-offs and edge cases.
Pro tip: Mention that you would use a sentinel head and tail to simplify edge cases in the linked list, and discuss how you would handle concurrency if needed, showing awareness of real-world scenarios.
Confirm the cache capacity, whether it's thread-safe, and the expected behavior for get and put operations. Ask about eviction policy (LRU) and any constraints.
Explain that a hash map provides O(1) access to nodes, and a doubly linked list maintains the order of usage. The combination allows O(1) get and put.
Detail how get moves the accessed node to the front (most recently used), and put adds or updates a node, evicting the least recently used (tail) if capacity is exceeded.
Write pseudocode or actual code for get and put, using helper functions for adding to front and removing nodes. Handle edge cases like updating an existing key.
State the time and space complexity (O(1) time, O(capacity) space). Discuss alternatives like using an ordered dictionary or a different eviction policy, and mention concurrency considerations.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.