206. Reverse Linked List

 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         ListNode* pre = NULL ;
13         while(head){
14             ListNode* temp = head->next ;
15             head->next = pre ;
16             pre = head ;
17             head = temp ;
18         }
19         return pre ;
20     }
21 };