class Solution {
public:
ListNode* swapPairs(ListNode* head) {
if (!head || !head->next) return head;
ListNode *t = head->next;
head->next = swapPairs(head->next->next);
t->next = head;
return t;
}
};leetcode 24 Swap Nodes in Pairs
原文：http://www.cnblogs.com/wangkun1993/p/6388174.html