Implement LRU Cache with without recursion
Last updated: November 16, 2025
Quick Overview
Implement a Deque data structure that supports get and put operations in O(log n) time.
HRT
November 16, 20253
12
289 solved
Implement a Deque data structure that supports get and put operations in O(log n) time.
HRT 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
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
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 is the worst-case input for your solution?
- What if the input doesn't fit in memory?
- How would your solution change if the input was sorted?
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Practice DSA ProblemsSample Answer
Problem Analysis
To implement an LRU (Least Recently Used) Cache, we need to efficiently manage the order of elements based on their usage. Here, we can utilize a combination of a hash map and a doubly linked list. Th...
Approach
- Data Structures: Use a hash map to store key-value pairs (where the key is the cache key and the value is a node in the doubly linked list). The doubly linked list will store the keys in order ...
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