What are the advantages and disadvantages of Arrays?

Difficulty: 4/10

random access, memory layout, resizing

Array Trade-offs

Arrays are highly efficient when workloads require indexed access and sequential traversal. Their main limitation is that fixed-size arrays cannot grow automatically, while insertions and deletions away from the end can require shifting elements.

1
Advantages: O(1) indexed access.
2
Advantages: excellent cache locality because elements are contiguous.
3
Advantages: low per-element memory overhead.
4
Advantages: efficient sequential iteration.
5
Disadvantages: fixed-size arrays cannot grow without reallocation.
6
Disadvantages: middle insertion and deletion are O(n).
7

Scenario Questions

0-2 years experience

1If you need to store a list of user IDs that you’ll frequently access by index, how would you implement it with an array, and what happens if you need to add an element beyond its current size?
2Can you explain what happens in memory when you declare an int[10] in Java versus a List<Integer>?

2-5 years experience

1We have a feature that processes a stream of events and stores the last 1,000 events in memory. We initially used an array but observed occasional OutOfMemory errors. Walk me through why that might happen and what alternative you’d consider.

Follow-up Questions

How does cache locality change when you switch from an array to a linked list?
What is the time complexity of inserting an element at the beginning of a large array?
When would you choose a dynamic array over a static one?