题解 | #输出单向链表中倒数第k个结点#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int n = Integer.parseInt(in.next());
            ListNode head = new ListNode(-1);
            ListNode tmp = head;
            for (int i = 0; i < n; i++) {
                ListNode node = new ListNode(in.nextInt());
                tmp.next = node;
                tmp = tmp.next;
            }
            int k  = Integer.parseInt(in.next());
            ListNode result = getKthVal(head.next, k);
            if (result != null) {
                System.out.println(result.val);
            }else{
                System.out.println(0);
            }
            
        }
    }

    public static ListNode getKthVal(ListNode head, int k) {
        if (head == null) {
            return null;
        }
        ListNode fast = head, slow = head;
        for (int i = 0; i < k; i++) {
            if (fast == null) {
                return fast;
            }
            fast = fast.next;
        }
        while (fast != null) {
            fast = fast.next;
            slow = slow.next;
        }
        return slow;
    }


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