Ermph, this is C specific and shouldn’t be extrapolated to other languages. Since you’re writing in C you are trying to show your chops as a low level programmer. Therefore, showing that you know how to implement a hash table is worthwhile, so you should do it yourself. You could add a comment to the code saying something to that effect. Again that’s just for C. Implementing your own hash table in Python instead of using the built-in one would be crazy. Implementing one in C++ instead of using the stdlib or some other one would have to be carefully justified.

I do have to wonder what you are up to in this day and age, pursuing what sounds like junior level C projects. I would say that whole approach is something of a dead end. You’re more employable with higher level languages than with C these days, I would have to say. Or if you write something in Python that incorporates some C functions that you write using Python’s C API, that shows you can operate at multiple levels at the same time, which is even better.