public class Solution {
	public ListNode reverseInPairs(ListNode head) {
	// corner case
	if (head == null || head.next == null) {
		return head;
	}
	// 记录一下第二、三个节点
	ListNode N2 = head.next;
	ListNode N3 = head.next.next;
	// subproblem：是以N3为头的LinkedList
	ListNode subHead = reverseInPairs(N3);
	//把所有的结点关系连起来
	N2.next = head;
	head.next = subHead;
	return N2;
	}
}

拓展延伸

Reverse Nodes in K-Group

LinkedList