The interview consisted of an online CodeSignal assessment with 4 random problems: one easy, two medium, and one hard. The last problem was particularly challenging and required knowledge of the Line Sweep algorithm to solve. I managed to solve it, though not optimally, and received 550/600 points. Looking back, that was the only challenging part of the entire interview process; everything else was quite easy, so overall I would rate the interview difficulty as easy.

The second round was supposed to be live coding. However, for some reason, I received a System Design question – a variation of a distributed view/likes/transactions counter. The third round was also System Design, focusing on a rate limiter. The last round was behavioral, which I seem to have failed. I haven't received proper feedback, so I don't know the exact reason.

It feels unfair because I dedicated a significant amount of time to these interviews and at least expected to receive constructive feedback to improve my lacking skills. Instead, I received the generic "We’ve reviewed your background and experience and unfortunately, we have decided to move ahead with other candidates." Not cool, Visa.

Design a transactions counter with high load of requests.