Implement Hash Map with in-place
Last updated: February 17, 2026
Quick Overview
Implement a hash map that supports in-place insertion, deletion, and retrieval of key-value pairs. Your solution should handle collisions using chaining or open addressing and must provide methods to add, remove, and get values based on keys. The expected time complexity for these operations should be O(1) on average.
Shopify
February 17, 202637
7
1,902 solved
Implement a hash map that supports in-place insertion, deletion, and retrieval of key-value pairs. Your solution should handle collisions using chaining or open addressing and must provide methods to add, remove, and get values based on keys. The expected time complexity for these operations should be O(1) on average.
This coding problem is frequently asked during Technical Screen at Shopify. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Shopify expects candidates to write production-quality code, not just solve the puzzle.
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
- Can you solve this in a single pass?
- How would your solution change if the input was sorted?
- What if the input doesn't fit in memory?
- What is the worst-case input for your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
To implement a hash map that supports in-place insertion, deletion, and retrieval of key-value pairs, we will use an array of linked lists (chaining) for collision resolution. This approach is suitabl...
Approach
- Initialize the Hash Map: Create an array of a fixed size (e.g., 10) that will store linked lists for chaining.
- Hash Function: Implement a simple hash function that maps a key to an index...
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