The exercise wasn't a literal reimplementation, there were some additional constraints rather than a generalized problem, but it was literally 3 or 4 lines of simple if-then statements.

And not that it mattered to the purpose of this question, but this team did frequently work with kernel, language runtime and container runtime source code.

> A surprising number of applicants who passed HR's screen failed at this stage.

Perhaps you didn't notice this part of the parent comment.

"surprising" indicates that the expectation was the candidates were supposed to be able to perform the task. Perhaps you read some sarcasm into the comment that wasn't explicit?

It wasn't a trick question or complicated in any way. It was something a first semester CS student could have done without hesitation.