package leetCode_24;

/**

* @author dimdark

* @date 2017-10-08

* @time 9:02 PM

*/

public class Solution {

class ListNode {

int val;

ListNode next;

ListNode(int x) {

this.val = x;

}

}

public ListNode swapPairs(ListNode head) {

if (head == null || head.next == null) return head;

ListNode dummyHead = new ListNode(-1);

dummyHead.next = head;

ListNode node = dummyHead;

ListNode pNode, qNode, rNode;

while (node.next != null && node.next.next != null) {

pNode = node.next;

qNode = pNode.next;

rNode = qNode.next;

node.next = qNode;

qNode.next = pNode;

pNode.next = rNode;

node = pNode;

}

return dummyHead.next;

}

}