Circular Linked List Python

# python circular linked list

class Node:

  def __init__(self,data):

    self.data = data

    self.next = None

class cl:

  def __init__(self):

    self.head = None

 

  def is_empty(self):

    return self.head is None

 

  def insert(self,value):

    new_node = Node(value)

    if self.is_empty():

      self.head = new_node

      new_node.next = self.head

    else:

      current = self.head

      while current.next != self.head :

        current = current.next

      current.next = new_node

      new_node.next = self.head

      self.head = new_node

 

  def display(self):

    current = self.head

    while current.next != self.head :

      print(current.data,'<->',end='')

      current = current.next

    print()

   

  def delete(self,value):

    current = self.head

    while current.next != self.head:

      if current.data == value:

        current.data = None

        current.data = current.next.data

        current.next = current.next.next

      current = current.next

    print("deleted.")

    self.display()

   

  def update(self,value,alternate):

    current = self.head

    while current.next != self.head:

      if current.data == value:

        current.data = alternate

      current = current.next

    print("updated.")

    self.display()

 

  def size(self):

    current = self.head

    size=0

    while current.next != self.head:

      size+=1

      current = current.next

    print(f"size of circular linked list: \n{size}")

   

l = cl()

for i in range(10):

  l.insert(i)

l.display()

l.delete(5)

l.insert(55)

l.display()

l.delete(1)

l.update(6,66)

l.size()

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output:

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9 <->8 <->7 <->6 <->5 <->4 <->3 <->2 <->1 <-> deleted. 9 <->8 <->7 <->6 <->4 <->3 <->2 <->1 <-> 55 <->9 <->8 <->7 <->6 <->4 <->3 <->2 <->1 <-> deleted. 55 <->9 <->8 <->7 <->6 <->4 <->3 <->2 <-> updated. 55 <->9 <->8 <->7 <->66 <->4 <->3 <->2 <-> size of circular linked list: 8

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