标签：ini constant span ant algorithm value nbsp color amp
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.
/** * Definition for singly-linked list. * public class ListNode { * int val; * ListNode next; * ListNode(int x) { val = x; } * } */ public class Solution { public ListNode swapPairs(ListNode head) { if(head == null || head.next == null){ return head; } ListNode dummy = new ListNode(0); dummy.next = head; ListNode cur = dummy; while(cur != null && cur.next != null && cur.next.next != null){ ListNode slow = cur.next; ListNode fast = cur.next.next; slow.next = fast.next; cur.next = fast; cur.next.next = slow; cur = slow; } return dummy.next; } }
标签：ini constant span ant algorithm value nbsp color amp
原文地址：http://www.cnblogs.com/joannacode/p/6012364.html
