Linked Lists: Basics and Operations

Introduction

• Linked lists are vital data structures in programming.
• We will cover basic topics, previously covered collections framework.
• Advanced topics like balancing concepts, linked lists, and algorithms will be discussed.
• Aim: To simplify the understanding of advanced data structures through practice.

Importance of Coding and Technology

• Technology has a significant impact on future careers.
• Focus on coding practice to match technological advancements.
• Coding interest can develop even in disinterested students with consistent practice.

What is a Linked List?

• A linked list is a list of elements (nodes) that are linked together.
• Visual representation: Each element points to the next, forming a chain.
• Types of linked lists: Single linked list, Double linked list, Circular linked list.

Comparing Linked Lists and Arrays

• Arrays have direct access (indexing) but require contiguous memory allocation.
• Linked lists provide dynamic memory allocation and efficient insertion/deletion.
• Insert operation in arrays has time complexity O(n); linked lists have O(1) for insertion.
• Searching in arrays has O(1) complexity; linked lists have O(n), as search requires traversing all elements.

Linked List Structure and Operations

• Linked list node contains data and next pointer/reference.
• Example structure:
  • Node class with data and reference to next Node.
• Visualize nodes linked like train coaches, with each coach containing elements and pointing to the next.
• Important properties:
  • No fixed size.
  • Non-continuous memory allocation.

Creating and Managing Nodes

• Create node class with data and next pointer.
• Use constructors to initialize node objects.
• Define a linked list class to manage node operations.

Implementing Basic Operations

1. Adding Nodes

• Add First: Inserting a new node at the beginning.
  • Update the new node's next to the current head and set it as the new head.
• Add Last: Inserting a new node at the end.
  • Traverse to the last node, update its next to the new node.

2. Printing the List

• Traverse through the list and print each node's data.
• Handle the case when the list is empty.

3. Deleting Nodes

• Delete First: Removing the node at the beginning.
  • Update head to the next node.
• Delete Last: Removing the node at the end.
  • Traverse to the second last node and update its next to null.

4. Checking the Size

• Keep a count of nodes, increment on add, and decrement on delete.
• Function to return the current size of the list.

Example Code:

• Node and Linked list classes with CRUD (Create, Read, Update, Delete) operations.

Advanced Linked List Types

• Single Linked List: Each node points to the next node.
• Double Linked List: Nodes have pointers to both next and previous nodes.
• Circular Linked List: Last node points back to the first node.

Applications of Linked Lists

• Suitable for frequent insertion/deletion while traversing.
• Optimal for implementation using collection framework (e.g., Java’s LinkedList class).
• Coding practice involves understanding which data structure is best suited for different operations.

Practice and Application

• Regular exercise on linked lists and related problems.
• Preparing for interviews and exams by leveraging the properties and operations of linked lists.