Choosing a STL container with uniqueness and which keeps insertion ordering

Question

I am unable to decide which STL container to use in the following case:

1. I want to preserve the order of insertion of the elements
2. The elements in the

Answer 1

There might be a good built in way to do this, but one rather simple way is to use both a hash_map and a list. Check the hash_map before each insertion, then insert into both. You'll want to encapsulate this in a class, probably.