first = frist.getNext();
helper.next = first;

package com.beyond.linkedlist;

import org.omg.CORBA.PUBLIC_MEMBER;

public class Josepfu {
 public static void main(String[] args){
  CircleSingleLinkedList name = new CircleSingleLinkedList();
  name.addBoy(5);
  name.showBoy();
  name.countBoy(1, 2, 5);
 }

}

//創(chuàng)建一個(gè)環(huán)形的單向鏈表
class CircleSingleLinkedList {
 // 創(chuàng)建一個(gè)first節(jié)點(diǎn),當(dāng)前沒有編號(hào)的
 private Boy first = new Boy(-1);

 // 添加小孩節(jié)點(diǎn),構(gòu)成一個(gè)環(huán)形的鏈表
 public void addBoy(int nums) {
  if (nums < 1) {
   System.out.println("nums 的值不正常");
   return;
  }
  Boy curBoy = null; // 輔助指針,幫助構(gòu)造環(huán)形鏈表
  // 使用for來創(chuàng)建我們的環(huán)形鏈表
  for (int i = 1; i <= nums; i++) {
   // 根據(jù)編號(hào),創(chuàng)建小孩節(jié)點(diǎn)
   Boy boy = new Boy(i);
   // 如果是第一個(gè)小孩
   if (i == 1) {
    first = boy;
    first.setNext(first);
    curBoy = first;
   } else {
    curBoy.setNext(boy);
    boy.setNext(first);
    curBoy = boy;
   }

  }

 }

 // 遍歷當(dāng)前的環(huán)形鏈表
 public void showBoy() {
  if (first == null) {
   System.out.println("沒有小孩!");
   return;
  }
  // 因?yàn)閒irst不能動(dòng), 因此我們?nèi)匀皇褂靡粋€(gè)輔助指針完成遍歷
  Boy curBoy = first;
  while (true) {
   System.out.printf("小孩的編號(hào)%d \n", curBoy.getNo());
   if (curBoy.getNext() == first) {
    break;
   }
   curBoy = curBoy.getNext(); // 后移
  }
 }

 // 根據(jù)用戶的輸入,計(jì)算出小孩出圈的順序
 /**
  * 
  * @param startNo  表示從第幾個(gè)小孩開始數(shù)數(shù)
  * @param countNum 表示數(shù)幾下
  * @param nums     表示最初有多少個(gè)小孩在圈子中
  */
 public void countBoy(int startNo, int countNum, int nums) {
  if (first == null || startNo < 1 || startNo > nums) {
   System.out.println("輸入數(shù)據(jù)有誤~");
   return;
  }
  // 創(chuàng)建所需要的輔助指針,幫助小孩出圈
  Boy helper = first;
  // 需求創(chuàng)建一個(gè)輔助指針helper, 事先指向該環(huán)形列表的最后這個(gè)節(jié)點(diǎn)
  while (true) {
   if (helper.getNext() == first) {
    break;
   }
   helper = helper.getNext();
  }

  //小孩報(bào)數(shù)前,將指針移動(dòng)到各自開始的位置,移動(dòng) k-1 次
  for (int i = 0; i < startNo-1; i++) {
   first = first.getNext();
   helper = helper.getNext();
  }
  
  //當(dāng)小孩報(bào)數(shù)時(shí), 讓first 和 helper 指針同時(shí)移動(dòng) m-1次, 然后出圈
  //這是一個(gè)循環(huán)操作,直到圈中只剩下一個(gè)小孩為止
  while (true) {
   if (helper == first) {
    break;
   }
   for (int i = 0; i < countNum-1; i++) {
    first = first.getNext();
    helper = helper.getNext();
   }
   System.out.printf("小孩%d出圈!\n",first.getNo());
   first = first.getNext();
   helper.setNext(first);
  }
  System.out.printf("最后留在圈中的小孩編號(hào)為:%d",first.getNo());
 }

}

//先創(chuàng)建一個(gè)Boy類, 表示一個(gè)節(jié)點(diǎn)
class Boy {
 private int no;
 private Boy next;

 public Boy(int no) {
  this.no = no;
 }

 public int getNo() {
  return no;
 }

 public void setNo(int no) {
  this.no = no;
 }

 public Boy getNext() {
  return next;
 }

 public void setNext(Boy next) {
  this.next = next;
 }

}