Algorithms—19.Remove Nth Node From End of List

思路：读入list中，考虑首位的因素，截断。

/**
* 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) {
List<ListNode> list=new ArrayList<ListNode>();
list=addlist(head, list);
if (list.size()==n) {
return head.next;
}
list.get(list.size()-n-1).next=n==1?null:list.get(list.size()-n+1);
return head;
}
public List<ListNode> addlist(ListNode head, List<ListNode> list){
if (head!=null) {
list.add(head);
}else {
return list;
}
return addlist(head.next, list);
}
}

耗时：304ms，中游