Insert/Delete/GetRandom in O(1) with TTL per item (follow-up)

Problem: Randomized Set with TTL (follow-up) Design a data structure that supports: insert(x): Insert element x. Return false if x already exists; otherwise insert and return true. remove(x): Remove element x. Return false if x does not exist; otherwise remove and return true. getRandom(): Return a uniformly random element from the current set. Goal: make the average time complexity as close to O(1) as possible. Follow-up: Maintain a TTL per item Extend the structure to support TTL (time-to-live): insert(x, ttl): insert x with a TTL. Once expired, an element should be treated as non-existent (must not be returned by getRandom(), and remove() should behave as if it is absent, potentially after cleanup). Describe a design that keeps time complexity optimized, and explain how you handle expired items in: insert(x, ttl) remove(x) getRandom() Testing (asked to explain verbally) Explain how you would test the data structure, covering at least: Basic behavior: insert/remove/getRandom Edge cases: calling getRandom() on an empty structure (define expected behavior) Duplicate inserts and removing non-existing elements Randomness: how to validate distribution statistically TTL: near-expiry, just-expired, and many-expired scenarios Constraints (for complexity discussion) Up to 1e5 operations 32-bit integer values (assumptions acceptable for discussion) Example Input insert 1 insert 2 getRandom remove 1 getRandom Output true true (1 or 2) true 2