206. Reverse Linked List

题目：

Reverse a singly linked list.

思路：

递归的方法

代码：

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    ListNode* reverseList(ListNode* head) {        if(head==NULL||head->next==NULL)            return head;        ListNode* p = head->next;        ListNode* n = reverseList(p);        head->next = NULL;        p->next = head;        return n;            }};