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题目：
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.
思路：/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) {
* val = x;
* next = null;
* }
* }
*/
public class Solution {
public ListNode swapPairs(ListNode head) {
ListNode h1 = new ListNode(0);
h1.next = head;
ListNode h2 = h1;
if(head == null || head.next == null)return head;
while(h2.next != null && h2.next.next != null){
ListNode temp = h2.next.next;
h2.next.next = temp.next;
temp.next = h2.next;
h2.next = temp;
h2 = h2.next.next;
}
return h1.next;
}
}LeetCode | #24 Swap Nodes in Pairs
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原文地址：http://blog.csdn.net/allhaillouis/article/details/44158913
