题解 | #删除链表的倒数第n个节点#

import java.util.*;

/*
 * public class ListNode {
 *   int val;
 *   ListNode next = null;
 *   public ListNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param head ListNode类 
     * @param n int整型 
     * @return ListNode类
     */
    public ListNode removeNthFromEnd (ListNode head, int n) {
        // write code here
        head = inverseListNode(head);
        ListNode dummyListNode = new ListNode(-1);
        dummyListNode.next = head;
        ListNode rightListNode = dummyListNode;
        for(int i = 0;i<n-1;i++){
          rightListNode = rightListNode.next;
        }
        ListNode cur = rightListNode.next;
        if(cur == null){
            return null;
        }
        rightListNode.next = cur.next;
        return inverseListNode(dummyListNode.next);
    }

    public ListNode inverseListNode(ListNode head){
        ListNode resultListNode = null;
        while(head != null){
            ListNode tmpListNode = head.next;
            head.next = resultListNode;
            resultListNode = head;
            head = tmpListNode;
        }
        return resultListNode;
    }
}