LeetCode 从链表中删除倒数第N个节点

从单链表中删除倒数第N个节点，要求之遍历一遍链表。

例子如下：

 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.

Java版本，

/**
 * 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(null == head || n <= 0) return head;
        ListNode myhead = head, tail = head;
        while(n > 0 && tail.next != null){
            tail = tail.next;
            n--;
        }
        if(n > 1) return head;//n > sizeOfList
        if(n == 1 && tail.next == null) return head.next;
        while(tail.next != null ){
            myhead = myhead.next;
            tail = tail.next;
        }
        myhead.next = myhead.next.next;
        return head;
    }
}