LeetCode 24. Swap nodes in linked list pairwise

Original URL: https://leetcode.cn/problems/swap-nodes-in-pairs/submissions/

About the exchange; https://blog.csdn.net/qq_34501351/article/details/126203341?spm=1001.2014.3001.5501 This question is also a problem of exchange; because the target node of the exchange can be obtained; a virtual head node is introduced; the previous node of the target node can be better obtained;easier;

 public ListNode swapPairs(ListNode head) {ListNode dummyHead = new ListNode(-1);dummyHead.next = head;ListNode cur = dummyHead;ListNode node = head;while(node != null) {ListNode frist = node;ListNode second = node.next;// There is only one number, no need to change it, return the resultif(second == null) {return dummyHead.next;}frist.next = second.next;second.next = frist;cur.next = second;cur = frist;node = frist.next;}return dummyHead.next;}