Implement Trie with O(n) time
Last updated: April 17, 2026
Quick Overview
Implement a Trie data structure that supports insert, search, and startsWith operations in O(n) time, where n is the length of the input string. Your implementation should efficiently handle multiple strings and provide accurate results for each operation. Ensure that the Trie can accommodate a large set of strings while maintaining optimal performance.
Roblox
April 17, 202670
6
4,034 solved
Implement a Trie data structure that supports insert, search, and startsWith operations in O(n) time, where n is the length of the input string. Your implementation should efficiently handle multiple strings and provide accurate results for each operation. Ensure that the Trie can accommodate a large set of strings while maintaining optimal performance.
Roblox uses this problem in the Technical Screen to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.
What the Interviewer Expects
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
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 modify your solution to handle streaming input?
- What if the input doesn't fit in memory?
- Can you solve this in a single pass?
- How would you parallelize this solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to implement a Trie data structure that can perform insert, search, and startsWith operations efficiently in time, where is the length of the input string. A Tri...
Approach
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Define the TrieNode Class: Each node will contain a dictionary to store child nodes and a boolean to indicate the end of a word.
Example: For the word 'cat', the root node will have chil...
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