19. Remove Nth Node From End of List(C++)

 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* removeNthFromEnd(ListNode* head, int n) {
12         ListNode myhead(0);
13         myhead.next=head;
14         ListNode *p=&myhead,*q=&myhead;
15         for(int i=0;i<n;i++) p=p->next;
16         while(p->next!=NULL){
17             p=p->next;
18             q=q->next;
19         }
20         q->next=q->next->next;
21         return myhead.next;
22     }
23 };