Singly Linked List

A Singly Linked List is a linear data structure where each element (called a node) points to the next element in the sequence, forming a chain.

Basic Structure

• Each node contains two parts: data and a pointer/reference to the next node.
• The last node points to NULL, indicating the end of the list.
• The first node is called the head.

Advantages

• Dynamic size — grows and shrinks as needed.
• Easy insertion/deletion compared to arrays (no shifting elements required).
• Efficient memory usage since nodes are allocated dynamically.

Basic Operations

• Insertion: Adding a node at the beginning, end, or specific position.
• Deletion: Removing a node from the beginning, end, or specific position.
• Traversal: Visiting each node to read or process data.

Example Implementation in Python

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

class SinglyLinkedList:
    def __init__(self):
        self.head = None

    def insert_at_beginning(self, data):
        new_node = Node(data)
        new_node.next = self.head
        self.head = new_node

    def print_list(self):
        current = self.head
        while current:
            print(current.data, end=" -> ")
            current = current.next
        print("None")

# Usage
sll = SinglyLinkedList()
sll.insert_at_beginning(10)
sll.insert_at_beginning(20)
sll.insert_at_beginning(30)
sll.print_list()  # Output: 30 -> 20 -> 10 -> None

This simple Python example creates and manipulates a singly linked list by inserting nodes at the beginning and printing the list.