◼ 删除链表中的节点 ：https://leetcode-cn.com/problems/delete-node-in-a-linked-list
◼ 反转一个链表：https://leetcode-cn.com/problems/reverse-linked-list
◼ 判断一个链表是否有环，（快慢指针 ：https://leetcode-cn.com/problems/linked-list-cycle/
◼ 移除链表元素
https://leetcode-cn.com/problems/remove-linked-list-elements/
◼ 删除排序链表中的重复元素
https://leetcode-cn.com/problems/remove-duplicates-from-sorted-list/
◼ 链表的中间结点
https://leetcode-cn.com/problems/middle-of-the-linked-list/solution/
