Reverse Nodes in k-Group k个数为一组翻转结点

/**

* Definition for singly-linked list.

* struct ListNode {

* int val;

* ListNode *next;

* ListNode(int x) : val(x), next(NULL) {}

* };

*/

class Solution {

public:

ListNode *reverseKGroup(ListNode *head, int k) {

if(head==NULL||head->next==NULL||k<2)

return head;

ListNode *nexthead=head;

for(int i=0;i<k;i++)

{

if(nexthead)

{

nexthead=nexthead->next;

}

else return head;

}

ListNode *newhead=reverseKGroup(nexthead,k);

ListNode *pre=NULL;

ListNode *curr=head;

while(curr!=nexthead)//在这错了好几次了

{

ListNode *temp=curr->next;

curr->next=pre?pre:newhead;

pre=curr;

curr=temp;

}

return pre;

}

};