When you say "fixed this" which "this" do you think they fixed? Are you imagining this is a hash table? It's not It's an adaptor which will use two other conta

When you say "fixed this" which "this" do you think they fixed? Are you imagining this is a hash table? It's not It's an adaptor which will use two other containers (typically std::vector) to manage the sorted keys and their associated values. The keys are sorted and their values are stored in the corresponding position in their own separate std::vector. If you already have sorted data or close enough then this type can be created almost for free yet it has similar affordances to std::map - if you don't it's likely you will find the performance unacceptable.