Remove Nth Node From End of List

RemoveNthNodeFromEndOfList .java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode removeNthFromEnd(ListNode head, int n) {
       if (head==null){
           return head;
       }   
       
       
       ListNode remove=head;
       ListNode last=head;
       ListNode preHead=new ListNode (-1);
       preHead.next=head;
       
       ListNode pre=preHead;
       
       while (n>1){
           
           if (last.next==null){
               return head;
           }
           
           last=last.next;
           n--;
       }
       
       
       while (last.next!=null){
           last=last.next;
           
           pre=pre.next;
           
           remove=remove.next;
       }
       
       pre.next=remove.next;
       
       return preHead.next; 
       
       
       
    }
}