Given a linked list, swap every two adjacent nodes and return its head.
For example,
Given 1->2->3->4, you should return the list as 2->1->4->3.
Your algorithm should use only constant space. You may not modify the values in the list, only nodes itself can be changed.
1 /** 2 * Definition for singly-linked list. 3 * public class ListNode { 4 * int val; 5 * ListNode next; 6 * ListNode(int x) { 7 * val = x; 8 * next = null; 9 * } 10 * } 11 */ 12 public class Solution { 13 public ListNode swapPairs(ListNode head) { 14 ListNode dummy=new ListNode(0); 15 dummy.next=head; 16 ListNode cur=dummy; 17 while(cur.next!=null&&cur.next.next!=null){ 18 ListNode nextNode=cur.next.next; 19 cur.next.next=nextNode.next; 20 nextNode.next=cur.next; 21 cur.next=nextNode; 22 cur=cur.next.next; 23 } 24 return dummy.next; 25 } 26 }
[Leetcode] Swap Nodes in Pairs
原文：http://www.cnblogs.com/Phoebe815/p/4039320.html