【leetcode】Remove Nth Node From End of List

Given a linked list, remove the nth node from the end of list and return its head.

For example,

Given linked list: 1->2->3->4->5, and n = 2.

After removing the second node from the end, the linked list becomes 1->2->3->5.
Note:
Given n will always be valid.
Try to do this in one pass.

 

class Solution {
public:
    ListNode *removeNthFromEnd(ListNode *head, int n) {
    
        int i=0;
        int j;
          ListNode *s=new ListNode(0);
           s->next = head;
        ListNode *p=s;
      
        //ListNode* dumy = new ListNode(0);
       
        ListNode *q=s;
        //p=head;
        //q=head;
   
        while(i<n)
        {
            p=p->next;
            i++;
            
        }
        
        while(p->next!=NULL)
        {
            p=p->next;
            q=q->next;
        }

        q->next=q->next->next;

       
        return s->next;
    }
};