Queue Implementation using Linked List

Why Linked List?

After understanding the array-based implementation of queues, we can see that linked lists offer several advantages:

1. Dynamic Size: No need to worry about fixed capacity or resizing
2. Memory Efficiency: Only allocate memory for elements that are actually in the queue
3. No Memory Wastage: Unlike arrays, we don’t have unused space at the front
4. No Resizing Overhead: No need to copy elements when resizing

Key Components

• Node: Each element in the queue is stored in a node containing:
  • Data: The actual value
  • Next: Reference to the next node
• Front Pointer: Points to the first node (for dequeue operations)
• Rear Pointer: Points to the last node (for enqueue operations)

Key Operations

• Enqueue: Add a new node at the rear
• Dequeue: Remove the node at the front
• Front/Peek: View the front node’s data
• isEmpty: Check if front pointer is null
• Size: Keep track of number of nodes

Brief Introduction

To understand queues better, watch this concise explanation:

Visual Representation

Interactive Playground

Try implementing a queue using a linked list! The playground below provides a template where you can code your own implementation. Please close the sidebar by clicking on the sidebar close icon to have a nicer coding experience.

Time Complexity

Memory Management

1. Allocation: New nodes are created during enqueue
2. Deallocation: Nodes are removed during dequeue
3. Memory Leaks: Always properly delete nodes in C++
4. Garbage Collection: Handled automatically in Python/JavaScript

Conclusion

In this section, we learned how to implement a queue using a singly linked list. We also learned about the time complexity of the operations and the memory management of the linked list. There are other types of queues like a circular queue, priority queue, double ended queue etc. which we will learn in future sections.