An Introduction to Linked Lists in Python

A linked list is a data structure used for storing a sequence of elements. It’s data with some structure (the sequence).

Implementation of Linked List

class LinkedList():
    def __init__(self):
        self.head = None
        
    def append(self, value):
        if self.head is None:
            self.head = Node(value)
        else:
            current_node = self.head
            while current_node.next is not None:
                current_node = current_node.next
            current_node.next = Node(value)
            
    def show_elements(self):
        current = self.head
        while current is not None:
            print(current.data)
            current = current.next
            
    def length(self):
        result = 0
        current = self.head
        while current is not None:
            result += 1
            current = current.next
        return result
            
    def get_element(self, position):
        i = 0
        current = self.head
        while current is not None:
            if i == position:
                return current.data
            current = current.next
            i += 1
        return None

How to reverse a Linked List?

def reverse(l):
    if l.head is None:
        return
    
    current_node = l.head
    prev_node = None
    
    while current_node is not None:
        # Track the next node
        next_node = current_node.next
        
        # Modify the current node
        current_node.next = prev_node
        
        # Update prev and current
        prev_node = current_node
        current_node = next_node
        
    l.head = prev_node

Real World Applications of Linked Lists

1. Image viewer — Previous and next images are linked, hence can be accessed by next and previous button.
2. Previous and next page in web browser — We can access previous and next url searched in web browser by pressing back and next button since, they are linked as linked list.
3. Music Player — Songs in music player are linked to previous and next song. you can play songs either from starting or ending of the list.