https://leetcode-cn.com/problems/swap-nodes-in-pairs/

点击查看【bilibili】

题目

给定一个链表，两两交换其中相邻的节点，并返回交换后的链表。
你不能只是单纯的改变节点内部的值，而是需要实际的进行节点交换。

示例

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  1. 输入：head = [1,2,3,4]
  2. 输出：[2,1,4,3]
  1. 输入：head = []
  2. 输出：[]
输入：head = [1]
输出：[1]

解答

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image.png

image.png

  1. n1=p.next
  2. n2= p.next.next
  3. p.next = n2
  4. n1. next= n2. next
  5. n2. next= n1

  6. p=n1

    答案

    var swapPairs = function(head) {
 let dummy = new ListNode();
 dummy.next = head
 let current = dummy
 // n1 n2不为空
 while(current.next != null && current.next.next != null) {
     let n1 = current.next;
     let n2 = current.next.next;
     current.next = n2;
     n1.next = n2.next;
     n2.next = n1;
     current = n1;
 }

 return dummy.next
};