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; *         next = null; *     } * } */public class Solution {    public ListNode removeNthFromEnd(ListNode head, int n) {        if(head == null ) {            return head;        }        ListNode fast = head;        ListNode slow = head;        for(int i = 0; i < n; i++) {            fast = fast.next;        }        if(fast == null) {            return head.next;        }        while(fast.next != null) {            fast = fast.next;            slow = slow.next;        }        slow.next = slow.next.next;                return head;    }}