Three stages, described by the firm
HRT sets out its software engineer process as a take-home test with a deadline, then roughly two phone interviews, then a full day of onsite interviews, virtual or in person.
On the take-home, the firm says candidates should "feel free to use resources that are available to you (books/internet) as a language reference", and puts the emphasis on testing your code and finding corner cases. Notably, it says coding style is not what is being marked - correctness and edge cases are.
Phone rounds cover systems knowledge, data structures and problem solving, plus programming relevant to the team you are targeting. The onsite covers programming ability and code quality, systems-level knowledge, and problem-solving approach.
On languages: the take-home may be restricted depending on the role; phone and onsite rounds use C++ or Python for some roles and allow a choice for others.
What it says it is actually measuring
This is the most useful part of the firm's guide, and it is the part candidates ignore. Alongside technical ability, HRT names:
- Collaboration - "How you like to work with others. Do you take hints well?"
- Teachability - whether you apply feedback from earlier rounds later in the process.
- Communication - being able to "effectively communicate previous projects... in an appropriate amount of detail".
Its concrete advice is to over-communicate: when you change approach, when you need thinking time, when you spot your own mistake, and when you want a hint.
Read those together and the picture is clear. Feedback given in round two and visibly applied in round four is being scored. So is asking for a hint well.
What to prepare
Corner cases as a habit. The firm names testing and edge cases explicitly, and says style is not the point. Write the test, not the flourish.
Algorithms at genuine depth, for engineering tracks. Candidate reports describe competitive-programming-flavoured problems at the harder end.
Narrate everything. "Over-communicate" is the firm's own word.
Your own past projects, at the right level of detail. Also named explicitly.
Practise the same formats
The question sets below are ours, written in the formats this process is reported to use. They are not HRT's questions, and nothing here reproduces any part of its assessment.