When to use a dictionary vs an array?
Company: Imc
Role: Software Engineer
Category: Software Engineering Fundamentals
Difficulty: hard
Interview Round: HR Screen
## Question
You’re implementing a feature and must choose between using an **array/list** or a **dictionary/hash map** to store and access data.
**Explain when you would use an array/list vs when you would use a dictionary/hash map.**
Cover:
- Typical access patterns (lookup by index vs lookup by key)
- Time complexity for common operations (lookup/insert/delete)
- Memory overhead trade-offs
- Ordering and iteration considerations
- Examples of real use cases for each
Quick Answer: This question evaluates understanding of data structures—arrays/lists versus dictionaries/hash maps—focusing on access patterns, time complexity for common operations, memory overhead, ordering and iteration characteristics.