Python program to search an element in a Circular Linked List

PythonServer Side ProgrammingProgramming

When it is required to search for an element in 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 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, to search for a specific node in the linked list 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 search_value(self,elem_to_search):
      curr = self.head;
      i = 1;
      flag_val = False;
      if(self.head == None):
         print("The list is empty");
      else:
         while(True):
            if(curr.data == elem_to_search):
               flag_val = True;
               break;
            curr = curr.next;
            i = i + 1;
            if(curr == self.head):
               break;
         if(flag_val):
            print("The element is present in list at position : " + str(i));
         else:
            print("The element is not present in list");
   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("Value 99 is being searched")
   my_cl.search_value(99)
   print("Value 0 is being searched")
   my_cl.search_value(0)

Output

Nodes are being added to the list
The list is :
21
54
78
99
27
Value 99 is being searched
The element is present in list at position : 4
Value 0 is being searched
The element is not present in list

Explanation

  • The ‘Node’ class is created.
  • Another class with required attributes is created.
  • Another method named ‘search_value’ is defined, that is used to search for a specific element in the linked list.
  • 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 ‘search_value’ method is called.
  • It iterates through the list, and checks to see if the element that needs to be searched is found.
  • If it is found, its index is displayed.
  • This is displayed on the console using the ‘print_it’ method.
raja
Published on 11-Mar-2021 11:26:51
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