LeetCode-Remove Nth Node From End of List

题目：

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.

代码如下：

另解：两个相隔n个节点的指针同时移动，当前面的指针移到最后时，后面的指针跳过下一个节点（被删除的节点）；