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.

 

/**
 * 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) {
        if (head == null || n < 1) {
        	return head;
        }
        ListNode cur = head;
        while (cur != null) {
        	n--;
        	cur = cur.next;
        }
        if (n == 0) {
        	head = head.next;
        }
        while (n < 0) {
        	cur = head;
        	while (++n != 0) {
        		cur = cur.next;
        	}
        	cur.next = cur.next.next;
        }
        return head;
    }
}