题解 | #输出单向链表中倒数第k个结点#

import java.util.*;
public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            int nums = sc.nextInt();
            SingleLinkList singleLinkList = new SingleLinkList();
            for (int i = 1; i <= nums; i++) {
                ListNode node=new ListNode(sc.nextInt());
                singleLinkList.add(node);
            }
            int index=sc.nextInt();
            int len=singleLinkList.getLengthNode();
            int k=len-index+1;
            ListNode resNode=null;
            resNode=singleLinkList.find(k);
            if(index==0){
                System.out.println(0);
            }else{
                if(resNode!=null){
                     System.out.println(resNode.val);
                 }
            }
        }

    }
}

class SingleLinkList{
    //创建一个头节点，并初始化为0，此处头节点不存储题目的值
    private ListNode head = new ListNode(0);
    public void add(ListNode listNode) {
        ListNode curNode=head;
        while (true) {
            if (curNode.next == null) {
                break;
            }
            curNode=curNode.next;
        }
        curNode.next=listNode;
    }
    public ListNode find(int k){
        ListNode curNode=head.next;
        int count=0;
        while (true) {
            if (curNode == null) {
                return null;
            }
            count++;
            if (count == k) {
                return curNode;
            }
            curNode = curNode.next;
        }
    }

    public int getLengthNode() {
        ListNode curNode=head.next;
        int count=0;
        while (true) {
            if (curNode == null) {
                break;
            }
            count++;
            curNode = curNode.next;
        }
        return count;
    }
}

class ListNode{
    int val;
    ListNode next;

    public ListNode(int val) {
        this.val=val;
    }
}