std::unordered_multiset<Key,Hash,KeyEqual,Allocator>::rehash
Min standard notice:
Changes the number of buckets to a value n that is not less than count and satisfies n >= size() / max_load_factor(), then rehashes the container, i.e. puts the elements into appropriate buckets considering that total number of buckets has changed.
# Declarations
void rehash( size_type count );
(since C++11)
# Parameters
count: lower bound for the new number of buckets
# Return value
(none)
# Notes
rehash(0) may be used to force an unconditional rehash, such as after suspension of automatic rehashing by temporarily increasing max_load_factor().