Morningstar C++ Software Developer interview questions

Had a terrible interview experience with this company. Do not recommend even trying. First, agreed for an interview. It was cancelled couple of days before the interview with "we decided not to hire at all". Next week, I got a recruiter call saying "they want to hire again". Process 1) coding exercise at your own time 2) 2h interview - exercise overview, coding questions, system design, behavioural all in one. Was interrupted in the middle of 2h interview, saying good luck with your job search, even though I felt it was going good. I didn't answer 1 question well enough, so they decided it is a dealbreaker. 2 weeks later I see they started to hire for this position again (because some other recruiter called me). Doesn't seem to me they are even interesting in hiring OR position isn't important for the business needs.