https://www.gamedev.net/forums/topic/582613-c-how-is-unordered_set-implemented/ says
“unordered_set is typically implemented as a linked list that holds all the elements and a hash table stores pointers to the linked list nodes.”, echoed on https://stackoverflow.com/questions/31112852/how-stdunordered-map-is-implemented
LinkedHashMap.java?
keep learning 活到老学到老 