Context

Engineering managers at Western Digital often evaluate whether a candidate can solve a coding problem and clearly justify the performance of the chosen approach. This question focuses on explaining complexity, not just writing code.

Core Question

Given a simple algorithmic solution such as finding a target value in a list or checking duplicates in a Western Digital device ID stream, explain the time complexity of your approach.

Your explanation should address:

1. How many times the main loop or operation runs.
2. Which operations are constant time versus dependent on input size.
3. Why the final complexity is better or worse than an alternative approach.

For example, compare a brute-force nested-loop solution with a hash-table-based solution for duplicate detection.

Scope Guidance

The interviewer expects a clear Big O explanation, not a proof from formal complexity theory. You should be able to walk through the algorithm step by step, identify the dominant operation, and state both time and space complexity accurately.