只用了叠代，等會看一下大神的遞歸解法；

 1 /**
 2  * Definition for singly-linked list.
 3  * struct ListNode {
 4  *     int val;
 5  *     ListNode *next;
 6  *     ListNode(int x) : val(x), next(NULL) {}
 7  * };
 8  */
 9 class Solution {
10 public:
11     ListNode* reverseList(ListNode* head) {
12         if
 
(head==NULL||head->next==NULL) return head;
13         ListNode* pre,*cur;
14         pre=head;cur=head->next;
15         head->next=NULL;
16         while(cur!=NULL){
17             ListNode* temp;
18             temp=cur->next;
19             cur->next=pre;
20             pre=cur;
 
21             cur=temp;
22         }
23         return pre;
24     }
25 };

leetcode 206 反轉鏈表 Reverse Linked List