说明：  队列，又称为伫列（英文queue），是先进先出（FIFO, First-In-First-Out）的线性表。在具体应用中通常用链表或者数组来实现。队列只允许在后端（称为rear）进行插入操作，在前端（称为front）进行删除操作。
(Queue, also known as queue (English queue), is the first in first out (FIFO, First-In-First-Out) linear form. In specific applications, typically as a linked list or array to achieve. Queue only in the back-end (called the rear) to insert in the front end (called the front) for deletion.)