leetcode链表--15、everse-nodes-in-k-group（按照k值进行k个结点的逆序）

 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 *reverseKGroup(ListNode *head, int k) {
12         if(head == NULL || k<=1)
13             return head;
14         ListNode *pNode = head;
15         stack<ListNode *> s;
16         stack<ListNode *> s1;
17         int tmp = 0;
18         ListNode *h = new ListNode(0);
19         ListNode *h1 = h;
20         while(pNode)
21         {
22             if(tmp < k)
23             {
24                 s.push(pNode);
25                 pNode = pNode->next;
26                 tmp++;
27             }
28             else
29             {
30                 while(!s.empty())
31                 {
32                     h1->next = s.top();
33                     s.pop();
34                     h1 = h1->next;
35                 }
36                 tmp = 0;
37             }
38         }
39         if(tmp == k)
40         {
41             while(!s.empty())
42             {
43                 h1->next = s.top();
44                 s.pop();
45                 h1 = h1->next;
46             }
47         }
48         else
49         {
50             while(!s.empty())
51             {
52                 s1.push(s.top());
53                 s.pop();
54             }
55             while(!s1.empty())
56             {
57                 h1->next = s1.top();
58                 s1.pop();
59                 h1 = h1->next;
60             }
61         }
62         h1->next = NULL;
63         return h->next;
64     }
65 };