Lucy's Note of Coding

public class Test {

  public static void main(String[] args) {

    //Josephus problem
    CircularLinkedList circularLinkedList = new CircularLinkedList();
    int childNums = 125;
    circularLinkedList.addChild(childNums);
//    circularLinkedList.showAllChild();
    circularLinkedList.getOutFrequencyChildNode(10, 20, childNums);

  }
}

class CircularLinkedList {
    // declare first child
    Child first = null;



  /**
   * 將小孩節點加入環形鏈接串列
   * @param nums 加入的節點數
   */
  public void addChild(int nums) {
      // validate nums is valid
      if (nums < 1) {
        System.out.println("傳入的數量有誤！");
        return;
      }
      // now current node is first child
      first = new Child(1);
      Child current = first;
      for (int i = 2; i <= nums; i++) {
        Child child = new Child(i);

        // afterward add more child nodes
        // current node point to next new node
        current.setNext(child);
        // current node move forward
        current = current.getNext();
      }
      // current node point to first child node
      current.setNext(first);
    }

    public void getOutFrequencyChildNode(int whichChildStart, int countTimes, int childNums) {
      // validate whichChildStart is vaild or not
      if (first == null || whichChildStart < 1 || whichChildStart > childNums) {
        System.out.println("起始為第幾個小孩輸入有誤，請重新輸入");
        return;
      }

      Child helper = first;
      // helper node position: pre node of the get out node
      // just move helper node to the end of node
      do {
        helper = helper.getNext();
      } while (helper.getNext() != first);
      // just move first node and helper node to (whichChildStart - 1) position
      for (int i = 0; i < whichChildStart - 1; i++) {
        first = first.getNext();
        helper = helper.getNext();
      }

      while(true) {
        // the circularLinkedList has only one node left
        if (helper == first) {
          break;
        }

        for (int i = 0; i < countTimes - 1; i++) {
          first = first.getNext();
          helper = helper.getNext();
        }
        // first node is get out node
        System.out.printf("環形鏈接串列出圈小孩節點編號：%d\n", first.getNo());
        // helper node points to the next of first node
        first = first.getNext();
        helper.setNext(first);
      }
      System.out.println("========================================");
      System.out.printf("最後留在圈中的小孩節點編號：%d\n", helper.getNo());
    }

  /**
   * 遍歷所有小孩節點
   */
  public void showAllChild() {
      if (first.getNext() == null) {
        System.out.println("環形鏈接串列為空~");
      }
      Child temp = first;
      do {
        System.out.printf("當前小孩編號為%d\n", temp.getNo());
        temp = temp.getNext();
      } while (temp != first);// continue loop
    }
}

class Child {
    private int no;
    private Child next;
    public Child(int no) {
      this.no = no;
    }

  public int getNo() {
    return no;
  }

  public Child getNext() {
    return next;
  }

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

  @Override
  public String toString() {
    final StringBuilder sb = new StringBuilder("Child{");
    sb.append("no=").append(no);
    sb.append('}');
    return sb.toString();
  }
}

如有敘述錯誤，還請不吝嗇留言指教，thanks!