单向环形链表

单向环形链表（Josepfu）

约瑟夫环（约瑟夫问题）是一个数学的应用问题：已知n个人（以编号1，2，3...n分别表示）按顺时针方向围坐在一张圆桌周围，每个人持有一个密码（正整数）。一开始任选一个整数作为报数上限值m，从第一个人开始顺时针自1报数，报到m时停止报数，报m的那个人出列，他的密码作为新的m值，从他在顺时针方向上的下一个人又开始重新从1报数，报到m的那个人出列又出列；依此规律重复下去，直到圆桌周围的人全部出列

/*
约瑟夫问题
 */
public class Josepfu {
    public static void main(String[] args) {
        //测试
        CircleSingleLinkedList circleSingleLinkedList = new CircleSingleLinkedList();
        circleSingleLinkedList.addBoy(5);
//        circleSingleLinkedList.showBoy();
        circleSingleLinkedList.countBoy(1,2,5);
    }
}

class CircleSingleLinkedList {
    private Boy first = null;

    public void addBoy(int nums) {
        if (nums < 1) {
            System.out.println("nums不正确");
            return;
        }
        Boy curBoy = null;
        for (int i = 1; i <= nums; i++) {
            Boy boy = new Boy(i);
            if (i == 1) {
                first = boy;
                first.setNext(first);
                curBoy = first;
            } else {
                curBoy.setNext(boy);
                boy.setNext(first);
                curBoy = boy;
            }
        }
    }

    public void showBoy() {
        if (first == null) {
            System.out.println("链表为空");
            return;
        }
        Boy curBoy = first;
        while (true) {
            System.out.printf("编号 %d \n", curBoy.getNo());
            if (curBoy.getNext() == first) {
                break;
            }
            curBoy = curBoy.getNext();
        }
    }

    //根据输入计算出圈顺序(不包括创建链表)
    public void countBoy(int startNo, int countNum, int nums) {
        if (first == null || startNo < 1 || startNo > nums) {
            System.out.println("输入错误");
            return;
        }
        Boy helper = first;
        while (true) {
            if (helper.getNext() == first) {
                break;
            }
            helper = helper.getNext();
        }
        for (int j = 0; j < startNo - 1; j++){
            first = first.getNext();
            helper = helper.getNext();
        }
        while (true){
            //圈中只有一人
            if (helper == first){
                break;
            }
            for(int j = 0; j<countNum-1;j++){
                first = first.getNext();
                helper = helper.getNext();
            }
            System.out.printf("编号 %d 出圈\n",first.getNo());
            first = first.getNext();
            helper.setNext(first);
        }
        System.out.printf("编号 %d 出圈",first.getNo());
    }
}

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;
    }
}