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Yes, Design Hit Counter is a common interview-style design question that appears in companies like Google, Amazon, and Facebook. It tests knowledge of data streams, sliding windows, and efficient data structure design.
A queue or a circular array works well for this problem. A queue maintains timestamps of hits and removes outdated ones, while a circular array stores aggregated counts per second for constant-time operations.
The optimal approach typically uses a fixed-size circular array of 300 buckets, each representing one second in the 5-minute window. By storing timestamps and counts per bucket, both hit and getHits operations can be handled in constant time while using only O(1) space.
The problem only cares about hits in the last 300 seconds, which naturally forms a sliding time window. Using a sliding window allows the system to discard outdated hits efficiently and keep only relevant data.