Something called aff_z, which was part of my engineering school's C examinations and was used as a "dummy" test to have students fail when coming back from holidays (our marking system implied that failing a test stopped the marking, so failing that dummy test would invalidate your whole test. Forces you to pay attention to moronic details). I did reuse it once or twice during interviews.
Anyways... I forgotten the exact formulation but it was something like this...
Write a function taking a single char parameter named c and returning nothing (void).
You function must satisfy the following requirements:
- if c is bigger or equal to 0, then print 'z' to standard output
- if c is stricly smaller than 0 , then print 'z' to standard output
- in any other case, print the letter 'z' to standard output
The sad thing is that not only some students would come up with extremely convoluted solutions when the answer is fairly obvious, but that some would even manage to fail.
And believe it or not, it did happen during interviews as well.
Running it in interviews was fairly fun, as some applicants would start writing the possible branches and then realize what is wrong (obviously, if you only ask them orally, that is quite understandable that they do so as you speak... but if you give it in writing, I find it puzzling...)
It's dumb, but I guess it's a minimalistic screening (similarly, when hiring JS programmers, I always ask how to declare a variable, and then depending on their answer whether or not using var makes any difference at all. Quite often a sad moment, honestly.)