type Node struct {
 value int
 next *Node
}

type Circle struct {
 tail *Node
 lenth int
}

// 增加节点：
func (c *Circle) add(value int) {
 newNode := &Node{value, nil}
 if c.lenth == 0 { //空链表中添加节点
 c.tail = newNode
 c.tail.next = newNode
 } else {
 newNode.next = c.tail.next
 c.tail.next = newNode
 c.tail = newNode
 }
 c.lenth += 1
 c.printCircle()
}

// 删除节点：
func (c *Circle) remove(v int) {
 if c.lenth == 0 {
 fmt.Println("空环")
 return
 } else if c.lenth == 1 && c.tail.value == v { //链表中只有一个节点的特殊情况
 c.tail = nil
 c.lenth = 0
 c.printCircle()
 return
 }
 pre := c.tail
 cur := c.tail.next // 头节点
 for i := 0; i < c.lenth; i++ {
 if cur.value == v {
  if cur == c.tail { //如果删除的节点是尾节点,需更新tail
  c.tail = pre
  }
  pre.next = cur.next
  c.lenth -= 1
  c.printCircle()
  return
 }
 pre = cur
 cur = cur.next
 }
 fmt.Println(v, "不在环中")
}

//打印节点：
func (c *Circle) printCircle() {
 if c.lenth == 0 {
 fmt.Println("空环")
 return
 }
 cur := c.tail.next // 头节点
 for i := 0; i < c.lenth; i++ {
 fmt.Printf("%d ", cur.value)
 cur = cur.next
 }
 fmt.Println()
}

func testCircle() {
 var circle *Circle = new(Circle)
 //for i := 1; i <=41; i++ {
 // circle.add(i)
 //}
 circle.add(1)
 circle.remove(10)
 circle.printCircle()
}

class Node:
 def __init__(self, value, next=None):
 self.value = value
 self.next = next

 def __str__(self):
 return str(self.value)

class Circle:
 def __init__(self):
 self.tail = None
 self.lenth = 0

 # 增加节点
 def add(self, v):
 new_node = Node(v)
 if self.lenth == 0: # 空链表中添加节点
  self.tail = new_node
  self.tail.next = new_node
 else:
  new_node.next = self.tail.next
  self.tail.next = new_node
  self.tail = new_node
 self.lenth += 1

 # 删除节点
 def remove(self, v):
 if self.lenth == 0:
  print("空环")
  return
 elif self.lenth == 1 and self.tail.value == v: # 链表中只有一个节点的特殊情况
  self.tail = None
  self.lenth = 0
  return
 pre = self.tail
 cur = self.tail.next # 头节点
 for i in range(self.lenth):
  if cur.value == v:
  if cur == self.tail: # 如果删除的节点是尾节点，需更新tail
   self.tail = pre
  pre.next = cur.next
  self.lenth -= 1
  return
  pre = cur
  cur = cur.next
 print(v, "不在环中")

 # 打印链表
 def print_circle(self):
 if self.lenth == 0:
  print('空环')
  return
 cur = self.tail.next # 头节点
 for i in range(self.lenth):
  print(cur, end=" ")
  cur = cur.next
 print()


def test():
 c = Circle()
 for i in range(10):
 c.add(i)
 c.print_circle()
 c.remove(0)
 c.print_circle()
 c.remove(10)
 c.print_circle()
 c.remove(9)
 c.print_circle()
 c.remove(4)
 c.print_circle()