In which STL containers is the hash table implemented?

In the standard template library (STL), hash tables are implemented in the following associative containers:

• std::unordered_set
• std::unordered_map
• std::unordered_multiset
• std::unordered_multimap

These containers use hashing for fast access to elements. On average, the search, insertion, and deletion operations have a time complexity of O(1). In the worst case (for example, in case of hash collisions), this complexity can reach O(n), where n is the number of elements.