The first stage of the interview is a coding challenge on HackerRank. Once started, it must be finished within two days to alleviate time pressure for a candidate.

The questions are not particularly tough, even though implementing some of the tasks does require some time. One would likely spend at least two hours.

However, I'm clueless about what criteria they apply to the whole experience. Regardless of me having solved all their tasks with all tests passed, they replied that they won't proceed with the process any further.

So, without any feedback—both positive and negative—this entire challenge seems like a complete waste of time.

Quiz about what data structures should be used in what cases, and some general questions about OOP concepts.

Tasks for designing a hierarchy of classes, sorting dates, etc.