删除倒数第N个节点

 1 class Solution {
 2 public:
 3     ListNode* removeNthFromEnd(ListNode* head, int n) {
 4         ListNode *dimmy=new ListNode(0);//加入头结点使得编程简单
 5         dimmy->next=head;
 6         ListNode *p=dimmy,*q=dimmy;
 7         int i=1;
 8         while(q->next&&i<=n){
 9             q=q->next;
10             i++;
11         }
12         while(q->next){
13             p=p->next;
14             q=q->next;
15         }
16         ListNode *k=p->next;
17         p->next=k->next;
18         delete k;
19         return dimmy->next;
20     }
21 };