# Insertion at Beginning in Circular Linked List in Python

## Insertion at Beginning in Circular Linked List in Python

In the realm of data structures, linked lists are fundamental. Among them, circular linked lists present a unique twist. They not only have the standard features of a singly linked list but also form a closed loop.

In this page, we will explore how to perform insertion at beginning in circular linked list using Python. We will cover different scenarios and techniques for inserting elements in terms of Naïve Approach and Optimized Approach.

## Understanding Circular Linked List Insertion

Linked lists are fundamental data structures, but circular linked lists add an extra layer of complexity and versatility. Inserting a node at the beginning of a circular linked list may seem straightforward at first glance, but there are multiple ways to achieve this, each with its own advantages and drawbacks.

In a circular linked list, the last node is connected to the first node, forming a closed loop. This unique structure allows for efficient traversal and certain operations, making it particularly useful in specific scenarios.

### Circular Linked List Algorithm :

1. Initialize: Create a structure for the linked list node, including data and a pointer to the next node.
2. Create an Empty Circular Linked List: Initialize a pointer, say head, to NULL to represent an empty list.
3. Insertion at the Start: To insert a new node at the beginning of the circular linked list:
• Create a new node with the desired data.
• If the list is empty (head is NULL), set the new node’s next pointer to itself and update head to point to the new node.
• If the list is not empty, set the new node’s next pointer to the current head.
• Update the last node’s next pointer to the new node (making it circular).
• Update head to point to the new node.

## Circular Linked List Insertion at Beginning in Python

For each Insertion operation, we need to consider the two cases.

• Naïve Approach
• Optimized Approach

### Naïve Approach for Insertion at Beginning in Circular Linked List

#### Step 1: Create a New Node

• To add a new node at the start, first create a new node with the desired data

#### Step 2: Link the New Node

• Set the next pointer of the new node to the current head of the circular linked list.

#### Step 3: Update the Head

• Now, update the head pointer to point to the new node.

### Implementation of Circular Linked List in Python(Naïve Approach) :

```class Node:
def __init__(self, data):
self.data = data
self.next = None

new_node = Node(data)

# Traverse to the last node to update the next pointer
temp = temp.next

temp.next = new_node
```

### Optimized Approach for Insertion at Beginning in Circular Linked List

#### Step 1: Create a New Node

• Similar to the naïve approach, start by creating a new node with the desired data.

#### Step 2: Link the New Node

• Set the next pointer of the new node to the current head.

#### Step 3: Update the Last Node

• Find the last node in the circular linked list and update its next pointer to the new node.

#### Step 4: Update the Head

• Finally, update the head pointer to point to the new node.

### Implementation of Circular Linked List in Python(Optimized Approach) :

```class Node:
def __init__(self, data):
self.data = data
self.next = None

new_node = Node(data)

# Find the last node and update its next pointer
temp = temp.next

temp.next = new_node
```

### Time and Space Complexity

#### Conclusion

In this page, we have discussed about concept of “Insertion at Beginning in Circular Linked Lists in Python” using both naïve and optimized approaches. While the naïve approach is simple to understand, the optimized approach offers improved efficiency with constant time complexity. Understanding the nuances of circular linked lists and their insertion methods can be invaluable in solving various programming challenges.

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Question 1.

What is a circular linked list?

A circular linked list is a type of linked list in which the last node points back to the first node, forming a closed loop.

Question 2.

What is the advantage of the optimized insertion approach in circular linked lists?

The optimized approach reduces the time complexity of insertion at the start from O(n) to O(1), making it more efficient.

Question 3.

How can I get started with circular linked lists in programming?

To get started, understand the basic structure of circular linked lists and practice implementing operations like insertion, deletion, and traversal.

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