TLDR; Don't waste your time by spending time on providing a solution for the take-home assignment and getting a weird interview later. The first take-home assignment was on the medium level of difficulty. I've provided the best solution in the context of complexity and proposed improvements. I was surprised that they do require thread safety at that level as there were no requirements regarding that. So I decided to talk about that in the interview. Anyway, they liked my solution so I had an interview with their engineer, which was the most hilarious interview in my career. The interviewer asked "leet code easy" - I provided a solution and we spent some time because the interviewer was not able to evaluate the solution! Confused 2-pointer solution with the sliding window and trying to find a corner case where my solution doesn't work - he failed to find any. Next, asked a couple of easy C++ questions - all of them were not even on the regular developer level and were pretty weird. Responded to all of them and we finished 20 min earlier. In addition, the interviewer was not aware of my take-home assignment solution so we can't talk about that. They haven't provided any other feedback than "We don't want to proceed further" so think again about wasting a couple of hours on the take-home assignment trying to get decent performance being later rejected by the incompetent interviewer.

For now I had to implement one task and had technical interview It was not strict on c++ but related to task which they gave me. For now they did not respond/waiting for next step .