Mastering Stacks and Queues: Fundamentals in Data Structures

Explore the world of stack and queue in data structures. Understand their differences, implementation, and real-world applications. Enhance your coding skills and algorithm design proficiency.

Mastering Stacks and Queues


Let's focus on Data Structures Interviews before learning about stack and queue. One of the most crucial topics in computer science is data structure, which is crucial for anybody who aspires to become a Software Development Engineer (SDE) in a product-based company. A solid understanding of data structures assists in the effective execution of tasks.

Many programming positions nowadays demand a deep understanding of data structures. They play a crucial role in coding interviews as well. Linear data structures like stacks and queues add or delete items in a specific order. Read on to learn more about stacks and queues with real-life examples. Additionally, we'll cover the pros, cons, and application of both data structures in this article.

What are Stacks?

A stack is a linear, abstract data type having a predetermined capacity used in programming. Elements are added or removed in a certain order. A linear data structure will expand or shrink if we add or remove an element since the components are arranged in a straight line. Push and pop functions are essential to its operation. Push adds components to the stack, whereas pop removes them from the stack.  

The main characteristic of a Stack is that it adheres to the "Last In, First Out" (LIFO) concept for adding and deleting the element, setting it apart from other data structures.

There are several examples from everyday life, such as a stack of dishes or books. Our browsers use the same methodology to monitor the most recent websites visited and the call history saved on mobile devices. The ability to undo and redo things on our computer is another excellent example of Stacks.

Pros and Cons of Stacks


  • For beginners, Stack is simple to understand and implement.
  • You may manage the allocation and deallocation of memory with this.
  • The Stack can be utilized when the variable isn't utilized outside of the function in any program.
  • Easy to use compared to lines
  • Recursive problem-solving is done via stacks.


  • In stacks, random access to elements is not conceivable.
  • Stacks are neither scalable nor adaptable.

Applications of Stacks

The stack data structure has numerous applications in programming. Below are a few of them:

  • It is a crucial component of the Java virtual machine.
  • Stacks can be used for backtracking or verifying if an expression's parentheses match.
  • A stack can be used to evaluate expressions containing operands and operators.
  • In web development, stacks are the data structures used to match HTML tags.
  • It can be used for string reversal or string parsing.
  • It can also be used to change the phrase from one form to another.

What are Queues?

Like a stack, a queue is a linear data structure with certain insertion and deletion limitations. Insertion happens at one end of a queue, while removal happens at the other end or opposite end. Queues are accessible from both ends: one end is used to enqueue and the other to dequeue data. However, you can only access a stack from one end.

The FIFO (First In, First Out) principle, which stipulates that the element added to the list first is the element deleted from the list first, is followed by the queue data structure.

You may better comprehend the queue data structure by using the example of a genuine movie ticket counter. The person who comes first at a movie ticket desk is always serviced first. And the last customer to come will undoubtedly be served last. These queues can perform various operations and have open endpoints on both sides.

Pros and Cons of Queues


  • Queues can be modified.
  • They can manage various data kinds.
  • Data queues are quick and efficient.


  • It is difficult to add and remove components from the center.
  • It is difficult to search queues easily. This is due to the fact that searching takes O(N) time.

Applications of Queues

The queue data structure has various applications in programming. Below are a few of them:

  • When some systems must share a resource, the queue serves as a waiting list. For instance, disc scheduling or CPU scheduling.
  • In switches and routers, queues are employed.
  • In communication systems, queues may be utilized to buffer messages, such as queues for messages in messaging systems or buffers in computer networks.
  • When data is transmitted sequentially in networking, the queue is utilized.
  • It helps media players keep track of their playlists.
  • Queues can be used to govern traffic flow in transportation systems, including highway and airport traffic management systems.

What is the Difference Between Stacks and Queues?

Here is the difference between both data structures, ie. Stacks and Queues to understand them better:



This data structure is linear. The items are taken out or put in at the same end.

This data structure is also linear. The items are taken out and put back in from two distinct ends.

The Last In, First Out (LIFO) concept is used. It implies that the final piece to be put is the first to be removed.

The First In, First Out (FIFO) concept is used. It implies that the first element to be added is the first to be withdrawn from the list.

In stacks, insertion and deletion are only possible from the top end of the list.

Insertion and deletion in queues take place from the opposing ends of the list. The deletion starts at the top of the list, and the insertion starts at the bottom.

In stacks, we just maintain one access reference to the list, called the top, constantly pointing to the final element.

Two pointers to the list are kept readily available in queues. The front pointer always points to the first element added to the list and is still there, while the rear pointer always points to the most recent member added.

Push and pop are two of the operations available in a stack. In contrast to the push operation, which inserts an element into a list, the pop action removes an element from a list.

Enqueue and dequeue are two of the operations used by queues. Enqueue operations add entries to queues, whereas dequeue operations remove components from queues.

Wrapping Up

The data structure is a necessary part of web development course because they allow for the storage and processing of data.  You'll utilize the stack and queue linear data structures in various challenging scenarios. They are the fundamental data structure used by the Java Collections Framework. They are used to store identical data and retrieve it in a predetermined order. This article gave you a fundamental understanding of the stack and queue data structures. The final tabular representation of stack and heap memory highlighted a few significant distinctions.


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