Traversal and Printing a Linked List in DSA Python - Build from Scratch

Traversal and Printing a Linked List

📖 Scenario: Imagine you have a chain of boxes, each holding a number and a link to the next box. This is like a linked list. You want to see all the numbers in order by opening each box one by one.

🎯 Goal: You will build a simple linked list with three nodes, then write code to go through the list from start to end and print all the values in order.

📋 What You'll Learn

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

Use a variable called head to point to the first node

Traverse the linked list using a variable called current

Print the values of all nodes in order separated by ' -> ' and ending with ' -> None'

💡 Why This Matters

🌍 Real World

Linked lists are used in many software systems to manage ordered data where items can be added or removed easily, like music playlists or undo history.

💼 Career

Understanding linked lists is fundamental for software developers, especially when working with low-level data structures or optimizing memory usage.

1

Create the linked list nodes

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 called node1, node2, and node3 with values 10, 20, and 30 respectively.

DSA Python

# Define the Node class and create three nodes
# Your code here

Hint

Start by defining the Node class with an __init__ method. Then create three nodes with the given values.

2

Link the nodes together

Set node1.next to node2 and node2.next to node3. Then create a variable called head and set it to node1.

DSA Python

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

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

# Link the nodes and set head
# Your code here

Hint

Connect the first node to the second, the second to the third, and set head to the first node.

3

Traverse the linked list

Create a variable called current and set it to head. Use a while loop that runs while current is not None. Inside the loop, print current.value followed by ' -> ' without a newline, then update current to current.next.

DSA Python

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

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

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

# Traverse the list and print values
# Your code here

Hint

Use a while loop to go through each node until you reach the end (None). Print each node's value followed by ' -> '.

4

Print the end of the list

After the while loop, print 'None' to show the end of the linked list.

DSA Python

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

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

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

current = head
while current is not None:
    print(str(current.value) + ' -> ', end='')
    current = current.next

# Print the end of the list
# Your code here

Hint

After printing all node values, print 'None' to show the list ends here.