两种用途非常广泛的特殊Ls:队列、栈 it is worthwhile,at least for reasons of algorithmic clarity,to think of queues and stacks as being in themselves data structures,rather than being merely special kinds of lists. in out out back front Queue Stack a FIFO list(First-In-First-Out) a LIFO list(Last-In-First-Out) We can then use specially devised elementary instructions such as "add X to queue A,"or"push X on stack S,"rather than obscure formulations that explicitly involve indices.两种用途非常广泛的特殊List：队列、栈 a FIFO list (First-In-First-Out) a LIFO list (Last-In-First-Out) it is worthwhile, at least for reasons of algorithmic clarity, to think of queues and stacks as being in themselves data structures, rather than being merely special kinds of lists. We can then use specially devised elementary instructions such as “add X to queue A,” or “push X on stack S,” rather than obscure formulations that explicitly involve indices