Delete Node at Beginning in DSA Python - Build from Scratch

Delete Node at Beginning in a Singly Linked List

📖 Scenario: Imagine you have a line of people waiting to buy tickets. Sometimes, the first person in line leaves. We want to update the line to show who is now first.

🎯 Goal: You will create a simple linked list, then remove the first person (node) from the line (list), and finally show the updated line.

📋 What You'll Learn

Create a singly linked list with exactly three nodes containing values 10, 20, and 30 in that order.

Create a variable called head that points to the first node.

Write code to delete the first node by updating head to the next node.

Print the linked list after deletion in the format: 20 -> 30 -> None.

💡 Why This Matters

🌍 Real World

Linked lists are used in real life to manage queues, playlists, or any ordered collection where items can be added or removed easily.

💼 Career

Understanding linked lists and how to manipulate them is important for software developers working with data structures, memory management, and efficient data processing.

1

Create a singly linked list with three nodes

Define a class called Node with an __init__ method that takes data and sets self.data and self.next. Then create three nodes with values 10, 20, and 30. Link them so the first node points to the second, and the second points to the third. Finally, create a variable called head that points to the first node.

DSA Python

# Define Node class and create linked list nodes
# Your code here

Hint

Start by defining the Node class. Then create three nodes and link them by setting the next attribute.

2

Prepare to delete the first node

Create a variable called temp and set it equal to head. This will help us keep track of the node we want to delete.

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

head = node1

# Create a variable temp and set it to head
# Your code here

Hint

Use temp = head to hold the first node before deleting it.

3

Delete the first node by updating head

Update the variable head to point to the next node after temp. This removes the first node from the 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

head = node1

temp = head

# Update head to the next node after temp
# Your code here

Hint

Set head = temp.next to remove the first node from the list.

4

Print the linked list after deletion

Use a while loop with a variable current starting at head. Print each node's data followed by ->. When the loop ends, print None.

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

head = node1

temp = head
head = temp.next

# Print the linked list starting from head
# Your code here

Hint

Use a loop to print each node's data followed by '->'. End with printing 'None'.