使用结构体打造链表中节点，使用指针将零散的节点串成链

表，进行链表的增加节点，查询某节点，删除某节点的操作

。

试着打造双向链表以及除了头指针还有尾指针的链表。

-Use the structure to create a linked list of nodes, using the pointer will be scattered nodes strung linked list, add a node to a linked list, search for a node, delete a node operation. Try to create a doubly linked list, and in addition to the linked list head pointer, tail pointer.