stack，queue

• Container adaptor: Almost all functions are implemented by calling the underlying deque; of course, it does not have to be deque, as long as the selected container can provide the interface functions required by stack and deque.

stack和queue可使用list，deque作底层容器；
queue不能使用vector，因为vector不提供pop_front,实际queue只要不使用pop，也可以用vector作底层容器，因为对于这些模板class来说，只有调用到对应的成员函数，编译器才会检查该调用是否合法;

• Both stack and deque do not allow traversal, so no iterators are provided: because they have to maintain the characteristics of first-in-last-out and last-in-first-out respectively;