Queue with unique entries in c++

Question

I need to implement a queue containing unique entries(no duplicates) in C or C++. I am thinking of maintaining a reference of elements already available in queue but that seems

Answer 1

queuing:

• use std::set to maintain your set of unique elements
• add any element that you were able to add to the std::set to the std::queue

dequeueing:

• remove element from std::queue and std::set