Architecture & LLD Preview
Autocomplete / Typeahead
Prefix search backed by a trie, ranked suggestions, and incremental updates.
A trie shares memory across common prefixes, and every node — not just leaves — caches its own pre-merged top-K completions, updated incrementally by walking from the affected leaf back up to the root. A query is a walk to the prefix node followed by a cache read.
Core Design Challenge
"Design autocomplete/typeahead. How do you return ranked suggestions on every keystroke without re-scanning and re-sorting the dataset each time?"
What You'll Learn:
- ✦Understanding eviction policies (LRU, LFU, FIFO)
- ✦Designing O(1) time complexity maps and list structures
- ✦Thread-safety, mutex locking, and concurrent read/write access
- ✦Managing memory boundaries and cache expiration policies