std::unordered_multiset::reserve

 void reserve( size_type count ); (since C++11)

Sets the number of buckets to the number needed to accomodate at least count elements without exceeding maximum load factor and rehashes the container, i.e. puts the elements into appropriate buckets considering that total number of buckets has changed. Effectively calls rehash(std::ceil(count / max_load_factor())).

Contents

Parameters

 count - new capacity of the container

(none)

Complexity

Average case linear in the size of the container, worst case quadratic.