My first instinct was to just use a random number and check if it was already drawn, which the interviewer let me finish before pointing out that gets slow as the deck empties.
Start by clarifying requirements and constraints, then design the Card class with suit and rank, and implement the deck using a Fisher-Yates shuffle or a random index swap to ensure uniform randomness without repeats. Discuss trade-offs between pre-shuffling and on-the-fly selection, and consider thread safety and reset behavior.
Pro tip: Mention that you would use a cryptographically secure random number generator if fairness is critical, and discuss how to handle deck exhaustion (e.g., throw an exception or auto-reshuffle) based on the use case.
Ask about constraints: should drawCard() be thread-safe? What happens when the deck is empty? Should the deck be resettable? Are there performance requirements?
Define a Card class with immutable suit and rank (e.g., enums). The Deck class holds a list of 52 cards and an index or remaining count.
Use Fisher-Yates shuffle to randomize the deck once, then draw sequentially. Alternatively, pick a random index from the remaining cards and swap with the last drawn position.
Decide behavior when deck is empty: throw an exception, return null, or automatically reshuffle. Ensure no repeats until all cards are drawn.
Compare pre-shuffling (O(n) setup, O(1) draw) vs. on-the-fly random selection (O(1) draw but requires tracking). Mention thread safety and randomness quality.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.