Spent the first few minutes thinking it was just an inverted index problem and almost rushed straight to a hashmap of word to sentence list.
Start by clarifying requirements and scale, then propose an inverted index using a hash map from words to sets of sentence IDs, plus a map from sentence IDs to sentences. Explain how to support efficient lookup and deletion, and discuss trade-offs and potential optimizations.
Pro tip: Mention that using a set for sentence IDs ensures O(1) deletion from the word's posting list, and consider discussing how to handle updates to sentences (e.g., if a sentence is edited) to show foresight.
Ask about expected data size, read/write ratio, and whether sentences can be updated. This shows you think about practical constraints before designing.
Propose a hash map from words to sets of sentence IDs (inverted index) and a hash map from sentence IDs to sentence text (forward index). Explain how these support lookup and deletion.
Walk through insertion, lookup, and deletion. For deletion, remove the sentence ID from each word's set and delete the sentence from the forward index.
Discuss time and space complexity for each operation. Mention alternatives like using a trie for prefix searches or a database for persistence.
Talk about handling updates, concurrency, memory optimization (e.g., using integer IDs), and scaling to distributed systems if needed.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.