在双向链表能完成各种插入节点,删除节点操作.与单链表上的插曲和删除操作不同,双向链表中插曲和删除可以同时修改两个方向上的指针.-Doubly linked list to complete various insert node, delete node operation. Episode, and delete operations on a single linked list, doubly linked list episode and delete pointer can modif