Implement Hash Map with with follow-up
Last updated: September 25, 2025
Quick Overview
Implement a Hash Map data structure that supports `get` and `put` operations in O(1) average time complexity. Your implementation should handle collisions using chaining or open addressing. The input will consist of key-value pairs for the `put` operation, and the output for the `get` operation should be the value associated with the given key, or null if the key does not exist.
Anduril
September 25, 20258
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3,518 solved
Implement a Hash Map data structure that supports `get` and `put` operations in O(1) average time complexity. Your implementation should handle collisions using chaining or open addressing. The input will consist of key-value pairs for the `put` operation, and the output for the `get` operation should be the value associated with the given key, or null if the key does not exist.
Coding interviews at Anduril focus on problem-solving approach as much as the final solution. The interviewer wants to see you break down the problem, consider edge cases, and optimize iteratively. Communication throughout the process is key.
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
- How would you modify your solution to handle streaming input?
- Can you optimize the space complexity of your solution?
- How would you test this solution thoroughly?
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Practice DSA ProblemsSample Answer
Problem Analysis
To implement a Hash Map that supports get and put operations with an average time complexity of O(1), we need to utilize a hash table. This data structure allows us to map keys to values efficient...
Approach
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Initialize the Hash Map: Create a class
HashMapthat initializes an array of a fixed size (e.g., 10) for the buckets, where each bucket is a list to handle collisions. -
Put Operation: ...
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