Which of the following statements is NOT correct?

Group of answer choices

C$++$ language provides a set of C$++$ class templates to implement common data structures, which is known as Standard Template Library $($STL$)$;

In STL$,$ a set is used to store a collection of elements and it does not allow duplicates;

In STL$,$ a map is used to store a collection of entries that consists of keys and their values. Keys must be unique, and values need not be unique;

Both set and map class templates in STL are implemented with arrays.