Python Linked List

A linked list is a type of linear data structure individual items are not necessarily at contiguous locations. The individual items are called nodes and connected with each other using links.

• A node contains two things first is data and second is a link that connects it with another node.
• The first node is called the head node and we can traverse the whole list using this head and next links.

Creating a Node Class

We have created a Node class in which we have defined a __init__ function to initialize the node with the data passed as an argument and a reference with None because if we have only one node then there is nothing in its reference.

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

Implementation of Simple 4 Nodes Linked List

Example: Below is a simple example to create a singly linked list with three nodes containing integer data.

class Node: def __init__(self, data): self.data = data self.next = None # Create nodes node1 = Node(15) node2 = Node(3) node3 = Node(17) node4 = Node(90) # Link nodes node1.next = node2 node2.next = node3 node3.next = node4 head = node1 # Head points to the first node # Traverse and print the linked list current = head while current: print(current.data, end=" -> ") current = current.next print("None") 

15 -> 3 -> 17 -> 90 -> None 

Basics

Linked lists come in different forms depending on how nodes are connected. Each type has its own advantages and is used based on problem requirements. The main types of linked lists are:

• Singly Linked List
• Doubly Linked List
• Circular Linked List

To practice problems related to linked list, refer to this article Linked List Data Structure