链表反转

 1 /*
 2 struct ListNode {
 3     int val;
 4     struct ListNode *next;
 5     ListNode(int x) :
 6             val(x), next(NULL) {
 7     }
 8 };*/
 9 class Solution {
10 public:
11     ListNode* ReverseList(ListNode* pHead) {
12         if(pHead == NULL)
13         {
14             return NULL;
15         }
16         
17         ListNode *pHeadNew = pHead;           //新链表的头结点
18         
19         ListNode *pCurrent = pHead -> next;   //将第二个结点作为当前结点
20         ListNode *pNext = NULL;  
21         
22         while(pCurrent != NULL)  
23         {
24             pNext = pCurrent -> next;
25             pCurrent -> next = pHeadNew; //更新当前链表的头结点
26             pHeadNew = pCurrent;
27             pCurrent = pNext;
28         }
29         
30         pHead -> next = NULL;              //将新链表的表头的下一结点指向空
31         return pHeadNew;
32     }
33 };