lintcode ----删除链表中倒数第n个节点

ListNode *removeNthFromEnd(ListNode *head, int n) {
// write your code here
if(head==NULL) return head;
ListNode *myhead = new ListNode(0);
myhead->next = head;
ListNode *p = myhead;
ListNode *q = myhead;
for(int i=0;i<n;i++)
{
p=p->next;
}
while(p->next!=NULL)
{
p=p->next;
q=q->next;
}
p=q->next;
q->next=q->next->next;
delete p;

return myhead->next;

}