Maybe I came into this article knowing too much about the solution, but I dont agree with commenters saying this is a poorly designed interview question. Its a blog post as well, not the format that would be presented to a candidate.

I think it has clear requirements and opportunities for nudges from the interviewer without invalidating the assessment (when someone inevitably gets tunnel vision on one particular requirement). It has plenty of ways for an interviewee to demonstrate their knowledge and solve the problem in different ways.

Ive run debounce interview questions that attempt to exercise similar competency from candidates, with layering on of requirements time allowing (leading/trailing edge, cancel, etc) and this queue form honestly feels closer to what Id expect devs to actually have built in their day to day.