Sort Elements of a Circular Linked List in Python

When it is required to sort the elements of a circular linked list, a ‘Node’ class needs to be created. In this class, there are two attributes, the data that is present in the node, and the access to the next node of the linked list.

In a circular linked list, the head and the rear are adjacent to each other. They are connected to form a circle, and don’t have ‘NULL’ value in the last node.

Another ‘linked_list’ class needs to be created that would have an initialization function, and the head of the node would be initialized to ‘None’.

Multiple methods are defined by the user to add node to the linked list, sort the linked list in ascending or descending order and to print the node values.

Below is a demonstration for the same −

Example

 Live Demo

class Node:
   def __init__(self,data):
      self.data = data
      self.next = None
class list_creation:
   def __init__(self):
      self.head = Node(None)
      self.tail = Node(None)
      self.head.next = self.tail
      self.tail.next = self.head
   def add_data(self,my_data):
      new_node = Node(my_data)
      if self.head.data is None:
         self.head = new_node
         self.tail = new_node
         new_node.next = self.head
      else:
         self.tail.next = new_node
         self.tail = new_node
         self.tail.next = self.head
   def sort_list(self):
      curr = self.head
      if(self.head == None):
         print("The list is empty")
      else:
         while(True):
            index_val = curr.next
            while(index_val != self.head):
               if(curr.data > index_val.data):
                  temp = curr.data
                  curr.data = index_val.data
                  index_val.data = temp
               index_val = index_val.next
            curr =curr.next
            if(curr.next == self.head):
               break;
   def print_it(self):
      curr = self.head
      if self.head is None:
         print("The list is empty");
         return;
      else:
         print(curr.data)
         while(curr.next != self.head):
            curr = curr.next
            print(curr.data)
         print("\n")
class circular_linked_list:
   my_cl = list_creation()
   print("Nodes are being added to the list")
   my_cl.add_data(21)
   my_cl.add_data(54)
   my_cl.add_data(78)
   my_cl.add_data(99)
   my_cl.add_data(27)
   print("The list is :")
   my_cl.print_it()
   print("The list is being sorted")
   my_cl.sort_list()
   print("The sorted list is : ")
   my_cl.print_it()

Output

Nodes are being added to the list
The list is :
21
54
78
99
27
The list is being sorted
The sorted list is :
21
27
54
78
99

Explanation

• The ‘Node’ class is created.
• Another class with required attributes is created.
• Another method named ‘sort_list’ is defined, that is used to sort the elements in the circular linked list in an ascending or descending order.
• Another method named ‘print_it’ is defined, that displays the nodes of the circular linked list.
• An object of the ‘list_creation’ class is created, and the methods are called on it to add data.
• An ‘init’ method is defined, that the first and last nodes of the circular linked list to None.
• The ‘sort_list’ method is called.
• It iterates through the list, and places the elements in their relevant position based on the value.
• This is displayed on the console using the ‘print_it’ method.