What are the best data structures to use to implement a set?

Question

C++ / C#

Hello, I was given the task to implement a class for working with sets, i.e. set will not help here, everything is on your own. The basic operations do not cause difficulties, but I just can’t stop at any one particular data structure. I don't know if the bit vector idea will do? Using an array is somehow too banal and not very efficient.
What data structure would you recommend?

Answer 1

binary trees are fine, since you need to quickly find the presence of such a value when inserting.