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) {
        ListNode fast = head;
        ListNode slow = head;//n > 0
        for(int i = 0; i < n; i++){
            if(fast == null) return head;
            fast = fast.next;
        }
        if(fast == null) return head.next;
        while(true){
            fast = fast.next;
            if(fast == null){
                slow.next = slow.next.next;
                return head;
            }
            slow = slow.next;
        }
    }
}