【LeetCode】Swap Nodes in Pairs 链表指针的应用

题目：swap nodes in pairs

<span style="font-size:18px;">/** * LeetCode Swap Nodes in Pairs  * 题目：输入一个链表，要求将链表每相邻的两个节点交换位置后输出 * 思路：遍历一遍即可，时间复杂度O(n) * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { *         val = x; *         next = null; *     } * } */package javaTrain; public class Train12 {public ListNode swapPairs(ListNode head) {if(head == null || head.next == null) return null;        ListNode pNode;        pNode = head;        while(pNode != null && pNode.next != null){        int temp;         temp = pNode.val;        pNode.val = pNode.next.val;        pNode.next.val = temp;        pNode = pNode.next.next;         }        return head;    }}</span>