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.

第三遍：

 1 /**
 2  * Definition for singly-linked list.
 3  * public class ListNode {
 4  *     int val;
 5  *     ListNode next;
 6  *     ListNode(int x) {
 7  *         val = x;
 8  *         next = null;
 9  *     }
10  * }
11  */
12 public class Solution {
13     public ListNode removeNthFromEnd(ListNode head, int n) {
14         ListNode header = new ListNode(-1);
15         header.next = head;
16         ListNode fast = header, cur = header, lazy = header;
17         for(int i = 0; i < n; i ++)
18             fast = fast.next;
19             
20         while(fast != null){
21             fast = fast.next;
22             lazy = cur;
23             cur = cur.next;
24         }
25         lazy.next = cur.next;
26         return header.next;
27     }
28 }