题解 | #【双指针】输出单向链表中倒数第k个结点#

import java.util.*;
import java.util.stream.*;
import java.util.regex.*;

public class Main {
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);

    // while (in.hasNextInt()) {
    //   // 方法一：不讲武德
    //   int n = in.nextInt();
    //   int[] a = new int[n];
    //   for (int i = 0; i < n; i++) {
    //     a[i] = in.nextInt();
    //   }
    //   int k = in.nextInt();
    //   System.out.println(a[n - k]);
    // }

    while (in.hasNextInt()) {
      // 方法二：ListNode 双指针
      int n = in.nextInt();
      ListNode node = new ListNode(in.nextInt());
      ListNode head = node;
      ListNode headK = node;

      for (int i = 1; i < n; i++) {
        node.next = new ListNode(in.nextInt());
        node = node.next;
      }
      int k = in.nextInt();

      while (head.next != null) {
        head = head.next;
        k--;
        if (k <= 0) {
          headK = headK.next;
        }
      }

      System.out.println(headK.val);
    }
  }
}

class ListNode {
  int val;
  ListNode next;

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

  @Override
  public String toString() {
    return String.valueOf(val);
  }
};