unordered set

When you need a collection of unique elements that allows for fast lookup, insertion, and deletion, unordered_set in C++ is like your best friend. It's part of the Standard Template Library (STL) and provides an efficient way to store and manage data.

Unlike set, which maintains order and uses a balanced tree structure, unordered_set relies on hash tables, delivering average constant time complexity for many operations.

This characteristic makes it particularly useful in scenarios where performance matters.