Wanna talk about... std::set?

Question

Recently I find lack of lessons about STL in the c++.
Container std::set is an associative container and header that need to be include for it is,
#include <set>;
std::set is an associative container that contains a sorted set of unique objects of type Key. 
Basic example:
https://code.sololearn.com/cott0N65Ga0c/#cpp
So let's share our tries with member functions in the comments, discuss issues and suggest solutions.
As for me most relevante reference is:
http://www.cplusplus.com/reference/set/set

Answer 1

Nice work .. 👍
std::set :-
http://en.cppreference.com/w/cpp/container/set
std::array:-
http://en.cppreference.com/w/cpp/container/array

Answer 2

@DT
Yes, it's usefull site too.