[Cs3] Rehash Function

[Mikhail Nesterenko]

> 
> For the hash table lab should the rehash function shrink the hash
> table as well as expand it? Or should we compare n with the current
> table size and reject the rehashing if n is smaller?
> 

We'll go by the specification of rehash() for unordered_map. If "n" is
less than the number of buckets, then it can be ignored. That is,
there is no need to "downsize" the hashmap.

Thanks,
--
Mikhail