Implement LRU Cache with with follow-up
Last updated: September 15, 2025
Quick Overview
Implement a Trie data structure that supports insert, delete, and lookup operations in O(1) time.
Netflix
September 15, 202538
8
4,378 solved
Implement a Trie data structure that supports insert, delete, and lookup operations in O(1) time.
Netflix uses this problem in the Onsite 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
- Recognize the underlying problem pattern (sliding window, two pointers, BFS/DFS, etc.)
- Discuss multiple approaches and trade-offs before coding
- Implement an optimal solution with clean, production-quality code
- Handle all edge cases including boundary conditions and invalid input
- Optimize both time and space complexity with clear justification
- Test your solution systematically with well-chosen examples
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
- What if the input doesn't fit in memory?
- How would you modify your solution to handle streaming input?
- How would you test this solution thoroughly?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to implement a Trie data structure that supports insert, delete, and lookup operations in O(1) time. This is a unique challenge because while tries are typically implemen...
Approach
- Data Structure Definition: Define a
TrieNodeclass containing an array of size 26 (for each letter in the alphabet) and a boolean to indicate if the node represents the end of a valid word. A...
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