leetcode--Remove Nth Node From End of List

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.

[java]  view plain  copy

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

原文链接http://blog.youkuaiyun.com/crazy__chen/article/details/45566815