[LeetCode] Rotate 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 
12     ListNode * rotateRight(ListNode *head,unsigned rotate_num){
13         if(!head) return NULL;
14         
15         ListNode *node = head,*tail = head,*ret = NULL;
16         unsigned length = 0;
17 
18 
19         while(node){
20             ++length;
21             node = node->next;
22             if(node) tail = node;
23         }
24 
25         rotate_num %= length;
26 
27         unsigned cur_num = 1;node = head;
28             while(cur_num++ != length-rotate_num)
29             node = node->next;
30 
31         tail->next = head;
32         ret = node->next;
33         node->next = NULL;
34     
35         return ret;
36     }
37     
38 };