206. Reverse Linked List

I had following code in first place.

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 *prev = head, *cur = head->next;  
14:      prev->next = NULL;  
15:      while (cur) {  
16:        ListNode *tmp = cur->next;  
17:        cur->next = prev;  
18:        prev = cur;  
19:        cur = tmp;  
20:      }  
21:      return prev;  
22:    }  
23:  };  

And here is the more concise one from top rated solution.

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