In §23.2.7 Unordered associative containers [unord.req] of the C++ standard table 91 describes the additional requirements a STL unordered associative container must meet. In this table the standar...

I'd like to know why one would ever use std::unordered_multiset. My guess is it has something to do with invalidations or non-invalidations of iterators after insert/erase, but maybe its something ...

Why is the worst case complexity of std::unordered_multiset insert is linear? I understand why is that the case for std::unordered_set (you have to check that inserted value is not in the set) but ...