Python program to search an element in a Circular Linked List

by Online Tutorials Library July 22, 2022

12. Python program to search an element in a Circular Linked List

In this program, we create a circular linked list and search a node in the list.

Consider, above example. Suppose we need to search for node 5. To solve this problem, we will iterate through the list and compare each node with 5. If a match is found, we will set the flag to true and prints out the position of the node 5. In this example, node 5 is present at position 2.

ALGORITHM:

Define a Node class which represents a node in the list. It has two properties data and next which will point to the next node.
Define another class for creating a circular linked list, and it has two nodes: head and tail.
search() will search for a node in the list:

Variable i will keep track of the position of the searched node.
The variable flag will store boolean value false.
Current will point to head node.
Iterate through the loop by incrementing current to current.next and i to i + 1.
Compare each node’s data with the searched node if a match is found, set the flag to true.
If the flag is true, prints the position of the searched node.
Else, print the message “Element is not present in the list”.

PROGRAM:

  #Represents the node of list.    class Node:        def __init__(self,data):            self.data = data;            self.next = None;         class CreateList:        #Declaring head and tail pointer as null.        def __init__(self):            self.head = Node(None);            self.tail = Node(None);            self.head.next = self.tail;            self.tail.next = self.head;                #This function will add the new node at the end of the list.        def add(self,data):            newNode = Node(data);            #Checks if the list is empty.            if self.head.data is None:                #If list is empty, both head and tail would point to new node.                self.head = newNode;                self.tail = newNode;                newNode.next = self.head;            else:                #tail will point to new node.                self.tail.next = newNode;                #New node will become new tail.                self.tail = newNode;                #Since, it is circular linked list tail will point to head.                self.tail.next = self.head;                        #Searches for a node in the list        def search(self,element):            current = self.head;            i = 1;            flag = False;            #Checks whether list is empty            if(self.head == None):                print(“List is empty”);            else:                while(True):                     #Compares element to be found with each node present in the list                    if(current.data ==  element):                        flag = True;                        break;                    current = current.next;                    i = i + 1;                    if(current == self.head):                        break;                if(flag):                    print(“Element is present in the list at the position :  ” + str(i));                else:                    print(“Element is not present in the list”);         class CircularLinkedList:        cl = CreateList();        #Adds data to the list        cl.add(1);        cl.add(2);        cl.add(3);        cl.add(4);        #Search for node 2 in the list        cl.search(2);        #Search for node in the list        cl.search(7);    

Output:

Element is present in the list at the position: 2  Element is not present in the list

Next TopicPython Programs

Python program to search an element in a Circular Linked List

12. Python program to search an element in a Circular Linked List

ALGORITHM:

PROGRAM:

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