Circular vs Linear Linked List Key Difference in DSA Python - Build Both Approaches

Understanding Circular vs Linear Linked List Key Difference

📖 Scenario: Imagine you have a group of friends sitting in a circle playing a game. Each friend holds hands with the next friend, and the last friend holds hands with the first friend, making a circle. This is like a circular linked list. Now imagine the same friends sitting in a straight line, where the last friend does not hold hands with anyone. This is like a linear linked list.

🎯 Goal: You will create a simple linked list with nodes and learn the key difference between a circular linked list and a linear linked list by linking nodes differently. You will then print the list to see how the nodes connect.

📋 What You'll Learn

Create a simple Node class with a value and a next pointer

Create a linear linked list with three nodes connected in a line

Create a circular linked list by connecting the last node back to the first node

Print the linked list nodes to show the difference between linear and circular

💡 Why This Matters

🌍 Real World

Circular linked lists are used in real-world applications like music playlists that repeat, or games where players take turns in a circle.

💼 Career

Understanding linked lists and their types is important for software developers working on data structures, memory management, and algorithms.

1

Create Node class and linear linked list

Create a class called Node with an __init__ method that takes value and sets self.value and self.next to None. Then create three nodes with values 1, 2, and 3. Link them linearly by setting node1.next = node2 and node2.next = node3. The last node's next should remain None.

DSA Python

# Define Node class and create three nodes linked linearly
# Your code here

Hint

Remember, each node should know its value and who comes next. The last node points to None in a linear list.

2

Create a variable to mark the start of the list

Create a variable called head and set it to node1 to mark the start of the linked list.

DSA Python

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

node1 = Node(1)
node2 = Node(2)
node3 = Node(3)

node1.next = node2
node2.next = node3

# Set head to node1
# Your code here

Hint

The head variable helps us know where the list starts.

3

Make the linked list circular

Change the linked list to be circular by setting node3.next = head so the last node points back to the first node.

DSA Python

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

node1 = Node(1)
node2 = Node(2)
node3 = Node(3)

node1.next = node2
node2.next = node3

head = node1

# Make the list circular by linking last node to head
# Your code here

Hint

Link the last node's next to the head to form a circle.

4

Print the circular linked list nodes

Write code to print the values of the circular linked list starting from head. Print exactly 6 nodes to show the circular nature. Use a current variable starting at head and a count variable to stop after 6 prints. Print each node's value followed by '->'. After printing 6 nodes, print '... (circular)'.

DSA Python

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

node1 = Node(1)
node2 = Node(2)
node3 = Node(3)

node1.next = node2
node2.next = node3

head = node1

node3.next = head

# Print 6 nodes from the circular linked list
# Your code here

Hint

Use a loop to print nodes and stop after 6 to avoid infinite printing.