Data structures in Python, Series 2 : Circular Linked List

Insertion in Circular Linked List : 

Circular linked list is a sequence of elements in which every element has link to its next element in the sequence and the last element has a link to the first element in the sequence.

Insertion

In a circular linked list, the insertion operation can be performed in three ways. They are as follows...

1. Inserting At Beginning of the list

2. Inserting At End of the list

3. Inserting At Specific location in the list

Inserting At Beginning of the list

We can use the following steps to insert a new node at beginning of the circular linked list...

Step 1: Create a newNode with given value.

Step 2: Check whether list is Empty (head == NULL)

Step 3: If it is Empty then, set head = newNode and newNode→next = head .

Step 4: If it is Not Empty then, define a Node pointer 'temp' and initialize with 'head'.

Step 5: Keep moving the 'temp' to its next node until it reaches to the last node (until 'temp →

next == head').

Step 6: Set 'newNode → next =head', 'head = newNode' and 'temp → next = head'.

class node():
    def __init__(self, data, Next = None):
        self.next = Next
        self.data = data
class circlist():
    def __init__(self):
        self.head = None
        self.next = None
        self.data = 0
    def add_node(self,data):
        if self.head == None:
            self.head = node(data)
            self.head.next = self.head
        else:
            b = self.head
            a = node(data,self.head)
           
            while b.next != self.head :
                b = b.next
            b.next = a
       
    def printl(self):
        a = self.head
        while a.next != self.head:
            print(f'{a.data}',end= '>>')
            a = a.next
        print(f'{a.data}',end= '>>')
        print(f'{self.head.data}')
if __name__ == '__main__':
    lis = circlist()
    lis.add_node(2)
    lis.add_node(3)
    lis.add_node(5)
    lis.printl()