https://cpprefjp.github.io/reference/unordered_set/unordered_set/cbegin.html
std::unordered_set::cbegin - cpprefjp C++日本語リファレンス
先頭の要素を指す読み取り専用イテレータを取得する。
unordered setstd
https://www.boost.org/doc/libs/1_38_0/doc/html/boost/unordered_set.html
Class template unordered_set
class templateunordered set
https://www.spicelang.com/std/data/unordered-set/
Unordered Set - Spice Programming Language
The fast, powerful, self-contained and programmer oriented systems language Spice.
unordered setprogramming languagespice