Implement a Trie-Based Autocomplete with Ranked Suggestions
Last updated: May 21, 2025
Quick Overview
Build a trie data structure that supports prefix-based autocomplete with frequency-ranked suggestions. Handle case-insensitive matching, fuzzy matching with edit distance, and dynamic updates as new completions are observed.
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May 21, 20256
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2,638 solved
Build a trie data structure that supports prefix-based autocomplete with frequency-ranked suggestions. Handle case-insensitive matching, fuzzy matching with edit distance, and dynamic updates as new completions are observed.
Autocomplete is fundamental to a code editor. This question tests your ability to implement a fast prefix search with ranking. While Cursor uses LLMs for intelligent completions, traditional autocomplete is still used for variable names, file paths, and command palettes.
What the Interviewer Expects
- Implement a trie with insertion and prefix search
- Rank suggestions by frequency and recency
- Support case-insensitive matching
- Handle dynamic updates efficiently as new completions are observed
- Discuss time and space complexity
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would you support fuzzy matching with a maximum edit distance of 2?
- How would you limit memory usage for very large vocabularies?
- How would you persist the trie across editor sessions?
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Practice DSA ProblemsSample Answer
Problem Analysis
In this problem, we need to build a trie data structure to support efficient prefix-based autocomplete functionality. The key operations are insertion of new words, prefix searching, and ranking sugge...
Approach
- Trie Node Structure: Create a
TrieNodeclass with a dictionary for children, a frequency counter, and a timestamp for recency. - Trie Structure: Create a
Trieclass that contains met...
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