The deque class is like a vector, but also supports fast insertion and deletion at the front of the deque. 顺序容器共享一组通用的已标准化的接口：如果两种顺序容器都提供某一操作，那么该操作具有相同的接口和含义。
In computer science, a double-ended queue (dequeue, often abbreviated to deque, pronounced deck) is an abstract data type that generalizes a queue, for which elements can be added to or removed from either the front (head) or back (tail). It is also often called a head-tail linked list, though properly this refers to a specific data structure implementation (see below).