Traversal of Circular Linked List in DSA Python - Build from Scratch

Traversal of Circular Linked List

📖 Scenario: Imagine you have a group of friends sitting around a round table. You want to greet each friend one by one, starting from a specific friend and going around the table until you come back to the same friend.

🎯 Goal: You will create a circular linked list representing friends sitting in a circle. Then, you will write code to visit each friend exactly once, starting from the first friend, and print their names.

📋 What You'll Learn

Create a circular linked list with exactly 4 nodes named 'Alice', 'Bob', 'Charlie', and 'Diana'.

Use a variable to keep track of the starting node.

Write a loop to traverse the circular linked list starting from the first node and print each friend's name once.

Print the names in the order they are visited.

💡 Why This Matters

🌍 Real World

Circular linked lists are used in real life to model situations where items repeat in a cycle, like players taking turns in a game or songs playing in a loop.

💼 Career

Understanding circular linked lists helps in software development roles that involve designing efficient data structures for scheduling, buffering, and cyclic processes.

1

Create nodes for the circular linked list

Create a class called Node with an __init__ method that takes name and sets self.name = name and self.next = None. Then create four nodes named node1, node2, node3, and node4 with names 'Alice', 'Bob', 'Charlie', and 'Diana' respectively.

DSA Python

# Define Node class and create four nodes named node1, node2, node3, node4
# Your code here

Hint

Start by defining a simple Node class with name and next attributes. Then create four nodes with the exact names given.

2

Link nodes to form a circular linked list

Link the nodes to form a circular linked list by setting node1.next = node2, node2.next = node3, node3.next = node4, and node4.next = node1. Also, create a variable called start and set it to node1.

DSA Python

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

node1 = Node('Alice')
node2 = Node('Bob')
node3 = Node('Charlie')
node4 = Node('Diana')

# Link nodes to form a circle and set start to node1
# Your code here

Hint

Connect each node's next to the following node, and the last node back to the first to make a circle. Remember to set the start variable.

3

Traverse the circular linked list

Write a while loop to traverse the circular linked list starting from start. Use a variable current initialized to start. Inside the loop, print current.name, then move current to current.next. Stop the loop when current is equal to start again after the first iteration.

DSA Python

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

node1 = Node('Alice')
node2 = Node('Bob')
node3 = Node('Charlie')
node4 = Node('Diana')

node1.next = node2
node2.next = node3
node3.next = node4
node4.next = node1

start = node1

# Traverse the circular linked list and print each name
# Your code here

Hint

Use a loop that runs at least once and stops when you come back to the start node. Use a flag variable to track the first iteration.

4

Print the traversal result

Run the program to print the names of the friends in the order they are visited. The output should be:
Alice
Bob
Charlie
Diana

DSA Python

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

node1 = Node('Alice')
node2 = Node('Bob')
node3 = Node('Charlie')
node4 = Node('Diana')

node1.next = node2
node2.next = node3
node3.next = node4
node4.next = node1

start = node1

current = start
first_pass = True
while first_pass or current != start:
    print(current.name)
    current = current.next
    first_pass = False

# Run the program to see the output

Hint

Run the full program to see the names printed in order. Each name should appear on its own line.