【leetcode】Reverse Linked List

 1 class Solution {
 2 public:
 3     ListNode* reverseList(ListNode* head) {
 4         if(head==NULL||head->next==NULL) return head;
 5 
 6         ListNode *p=head->next;
 7         ListNode *newhead=reverseList(head->next);
 8         head->next=NULL;
 9         p->next=head;
10         return newhead;
11 
12        } 
13 };