24. 两两交换链表中的节点https://leetcode.cn/problems/swap-nodes-in-pairs/solutions/2773835/24-liang-liang-jiao-huan-lian-biao-zhong-qm81 19. 删除链表的倒数第 N 个结点https://leetcode.cn/problems/remove-nth-node-from-end-of-list/solutions/2773862/19-shan-chu-lian-biao-de-dao-shu-di-n-ge-f4is 面试题 02.07. 链表相交https://leetcode.cn/problems/intersection-of-two-linked-lists-lcci/solutions/2773880/mian-shi-ti-0207-lian-biao-xiang-jiao-by-f694 142. 环形链表 IIhttps://leetcode.cn/problems/linked-list-cycle-ii/solutions/2773919/142-huan-xing-lian-biao-ii-by-joker-ek4-vhcr