leetcode24.txt

//Java
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
 /**
 * 利用三个游标进行改变即可，首先调动current，再调动first，最后调动second，然后跟新current循环
 * 注意！！！最后根性current的时候，first和second已经改变了
class Solution {
    public ListNode swapPairs(ListNode head) {
        ListNode dummy = new ListNode(0);
        dummy.next = head;
        ListNode current = dummy;
        while(current.next != null && current.next.next != null){
            ListNode first = current.next;
            ListNode second = current.next.next;
            current.next = second;
            first.next = second.next;
            second.next = first;
            current = current.next.next;
        }
        return dummy.next;
    }
}