I don't think they really want to hire someone. The interview questions they ask don't make sense at all. I worked for several years and interviewed at famous big companies and pre-IPO companies (hot startups), but no one gave me this feeling like they don't actually want to hire. They just want to let you know how difficult the questions they ask are. So, if you have a choice, you don't need to interview with them at all.

Write a runnable, complicated code which includes a medium algorithm and a hard operation.