One of them was a trivial UI design question in Qt/ QML and the rest were more to do with algorithms and coding in C/C++. The questions were very weird as there are online solutions available to most of them; so it gave the impression that - given they "know this" - they care more about genuine answers and candidates taking initiative when solving them. I submitted my answers 2 days ahead of the deadline and provided my own answers to all of them. They rejected me on the basis of one of the answers having an edge case bug in. So I was surprised by their black-and-white approach in their assessment as they turned blind eye to my other relevant experiences and technical skills relevant to the job.