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.
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/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { * val = x; * next = null; * } * } */public
class Solution { /** * This is a fundamental problem.<br> * * @param head --The head node of the input linked list * @return head of the rotated linked list * @author Averill Zheng * @version 2014-06-03 * @since JDK 1.7 */ public
ListNode swapPairs(ListNode head) { ListNode newHead = head; if(head != null
&& head.next != null){ ListNode currentNode = head; ListNode nextNode = currentNode.next; newHead = nextNode; currentNode.next = nextNode.next; nextNode.next = currentNode; ListNode previous = currentNode; currentNode = currentNode.next; while(currentNode != null
&& currentNode.next != null){ nextNode = currentNode.next; currentNode.next = nextNode.next; nextNode.next = currentNode; previous.next = nextNode; previous = currentNode; currentNode = currentNode.next; } } return
newHead; }} |
leetcode--Swap Nodes in Pairs,布布扣,bubuko.com
原文：http://www.cnblogs.com/averillzheng/p/3769122.html