[sicp-enjoyer]

Do you know about std::unique? Generally sets are a poor tool for removing duplicates.

[pixelesque]

Doesn't std::unique only generally work on consecutive items, and effectively requires the items to already be in a container (or at the very least have access to iterators to the items)?

If so, that sounds fairly limiting to me (i.e. potential extra storage - of duplicates, sorting required, etc).

[sicp-enjoyer]

This person is already putting sets inside vectors, so I don't think they are worried about storage.

But yes, you either need to stop occasionally and remove the duplicates or use a set, if the storage is prohibitive.

Otherwise in terms of performance, sorting and unique is much faster than inserting one element at a time in a set.