LeetNode 题解之Reverse Nodes in k-Group

1、题目描述

2、问题分析

这个题本质上还是按照链表翻转的思路来解，只是需要添加一些细节判断。

3、代码

 class Solution {
 public:
     ListNode* reverseKGroup(ListNode* head, int k) {
         if( !head || head->next == NULL || k <=  ){
             return head ;
         }

         ListNode dummy() ;
         ListNode* d = &dummy ;
         ListNode* p = head ;

         while( p != NULL ){
             ListNode* pm = p;
             int n = ;
             ListNode* nextNode ;
             while( pm != NULL && n < k ){
                 pm = pm->next ;
                 ++n;
             }
             if( pm != NULL ){
                 nextNode = pm->next;
                 pm->next = NULL ;

                 d->next = reverseList( p );
                 d = p;
                 p = nextNode ;     // k % number of nodes == 0 ,out of while ;

             }else{
                 d->next = p;
                 break;
             }

         }

         return dummy.next ;

     }

     ListNode* reverseList( ListNode* head  ){
         if( !head || head->next == NULL ){
             return head;
         }
         ListNode* p = head ;
         ListNode* q = head->next ;
         head->next = NULL ;
         while( p != NULL && q != NULL ){
             ListNode* tmp = q->next ;
             q->next = p;
             p = q ;
             q = tmp ;
         }
         return p ;

     }
 };