1         public static LinkedListNode SwapNodesinPairs2(LinkedListNode head)
 2         {
 3             if (head == null || head.Next == null)
 4                 return head;
 5 
 6             LinkedListNode fakehead = new LinkedListNode();
 7             fakehead.Next = head;
 8 
 9             LinkedListNode l1 = head;
10             LinkedListNode l2 = head;
11             LinkedListNode prev = fakehead;
12             LinkedListNode ret = head.Next;
13             LinkedListNode next = head;
14             
15             while (next != null && next.Next != null)
16             {
17                 l1 = next;
18                 l2 = next.Next;
19                 next = next.Next.Next;
20                 l2.Next = l1;
21                 l1.Next = next;
22                 prev.Next = l2;
23                 prev = l1;
24             }
25 
26             return ret;
27         }