Insert at End of Circular Linked List in DSA Python - Build from Scratch

Insert at End of Circular Linked List

📖 Scenario: You are managing a circular queue of tasks where the last task points back to the first task, forming a circle. You want to add a new task at the end of this circular list.

🎯 Goal: Build a circular linked list with initial tasks, then insert a new task at the end, and finally print the circular list to verify the insertion.

📋 What You'll Learn

Create a Node class with data and next attributes

Create a circular linked list with three nodes containing data 10, 20, and 30

Create a function insert_at_end(head, data) to insert a new node at the end

Print the circular linked list starting from head, showing all nodes once

💡 Why This Matters

🌍 Real World

Circular linked lists are used in real-time systems like task scheduling where the tasks repeat in a cycle.

💼 Career

Understanding circular linked lists helps in roles involving system programming, embedded systems, and designing efficient data structures.

1

Create Node class and initial circular linked list

Create a class called Node with attributes data and next. Then create three nodes with data 10, 20, and 30. Link them in a circular way so that the last node points back to the first node. Assign the first node to a variable called head.

DSA Python

# Define Node class and create circular linked list with nodes 10, 20, 30
# Your code here

Hint

Remember to link the last node's next to the first node to make the list circular.

2

Create a function to insert at end

Create a function called insert_at_end(head, data) that inserts a new node with the given data at the end of the circular linked list. The function should return the head of the updated list.

DSA Python

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

node1 = Node(10)
node2 = Node(20)
node3 = Node(30)

node1.next = node2
node2.next = node3
node3.next = node1

head = node1

# Define insert_at_end function below
# Your code here

Hint

Traverse the list until you reach the last node (which points back to head), then insert the new node after it.

3

Insert a new node with data 40 at the end

Call the function insert_at_end(head, 40) and assign the result back to head to insert a new node with data 40 at the end of the circular linked list.

DSA Python

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

node1 = Node(10)
node2 = Node(20)
node3 = Node(30)

node1.next = node2
node2.next = node3
node3.next = node1

head = node1

def insert_at_end(head, data):
    new_node = Node(data)
    if head is None:
        new_node.next = new_node
        return new_node
    current = head
    while current.next != head:
        current = current.next
    current.next = new_node
    new_node.next = head
    return head

# Insert new node with data 40 at the end
# Your code here

Hint

Assign the result of insert_at_end(head, 40) back to head.

4

Print the circular linked list

Write code to print the data of each node in the circular linked list starting from head. Print all nodes exactly once, separated by ->, and end with null.

DSA Python

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

node1 = Node(10)
node2 = Node(20)
node3 = Node(30)

node1.next = node2
node2.next = node3
node3.next = node1

head = node1

def insert_at_end(head, data):
    new_node = Node(data)
    if head is None:
        new_node.next = new_node
        return new_node
    current = head
    while current.next != head:
        current = current.next
    current.next = new_node
    new_node.next = head
    return head

head = insert_at_end(head, 40)

# Print the circular linked list
# Your code here

Hint

Use a loop to traverse nodes until you reach the head again, collecting data to print.