std::vector<bool>

std::vector<bool> is a specialization of the std::vector template class in C++ that is optimized for storing boolean values. Unlike the standard std::vector template class, which stores elements as contiguous blocks of memory, std::vector<bool> stores each boolean value as a single bit, packing multiple bits into a single byte.

This optimization allows std::vector<bool> to use less memory than a regular std::vector when storing large numbers of boolean values. However, it also introduces some complexity when accessing individual elements, as each boolean value must be extracted from its packed bit representation.

To make accessing individual elements easier, std::vector<bool> provides a specialized proxy class called std::vector<bool>::reference. This class acts like a boolean reference, but internally it works by manipulating the packed bit representation of the boolean value.

Overall, std::vector<bool> can be a useful tool for storing large numbers of boolean values in a memory-efficient manner, but it may also require some additional care and attention when accessing individual elements.