Given a linked list, remove the n^th 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.

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode removeNthFromEnd(ListNode head, int n) {
        ListNode p = head;
        while(n>0 && p!=null){
            p = p.next;
            n--;
        }
                
        ListNode newHead = new ListNode(1);
        newHead.next = head;
        ListNode q = newHead;       
        while(p!=null){
        	q = q.next;
        	p = p.next;
        }    
       
        q.next = q.next.next;
        return newHead.next;
    }
}