Stack Representation
A stack is a linear data structure that follows the Last-In-First-Out (LIFO) principle. This means that the last element added to the stack is the first one to be removed. It is an ordered collection of elements where insertion and removal of items occur at the same end, traditionally referred to as the "top." A stack can be visualised as a vertical structure with elements stacked on top of each other, resembling a stack of plates.
Think of a stack as a collection of items stacked one on top of the other, much like a stack of books where you add or remove books from the top.
Array Implementation
In an array-based implementation, you have an array where you maintain a variable called "top" that points to the index of the top element in the stack. When you push an element, you increment the "top" index and place the new element at that index.
Linked List Implementation
In a linked list-based implementation, each element of the stack is a node in the linked list. When you push an element, you create a new node, point it to the current top node, and update the top pointer to the new node.
Stack Operations
A stack is essentially a container that supports two main operations: push and pop.
Push Operation
The push operation involves adding an element to the top of the stack. Imagine a stack of plates where you place a new plate on top of the stack.
Pop Operation
The pop operation involves removing the top element from the stack. Think of it as taking the top plate from a stack of plates.
Peek Operation
The peek operation allows you to look at the top element without removing it. It's like looking at the top plate without taking it off the stack.
Both array and linked list implementations support the peek operation by accessing the element at the "top" index or the data in the top node, respectively.
Applications of Stack in Data Structure
1. Function Calls-
The state of the program is placed into the Stack when a function is invoked. The preceding function's execution is continued after the process returns by popping the state off the Stack.
2. Backtracking-
Stacks can be used for backtracking or to verify if an expression's parentheses match. Stacks are used by the backtracking method to maintain track of the stages of the solution process. The old state is removed from the Stack when the algorithm goes backwards after pushing the current state onto it.
3. Undo/Redo Operations-
Many apps' undo-redo functionality employs stacks to remember the prior operations. A new action is added to the Stack each time it is completed. The top member of the Stack is popped to undo the action, and the original procedure is then carried out.
4. Web browser history-
Stacks are used by web browsers to record the websites you visit. When you click the back button, the previous URL is removed from the Stack and is added to the Stack each time you visit a new page.
5. Reverse the Data-
We must reorganize the data so that the first and final items are switched; the second and second-last elements are exchanged, and so on for all subsequent elements if we want to reverse a particular collection of data.
For example: If we have string codingNinja, then on reversing, it will become ajniNgnidoc.
6. Parenthesis checking-
To determine if brackets are balanced or not, a stack data structure is utilized. An opening parenthesis is popped off the Stack as a closing parenthesis is added onto it. The brackets are balanced if the Stack is empty at the conclusion of the expression.
7. Expression Evaluation-
Expressions written in infix, postfix, and prefix notations are evaluated using a stack data structure. The Stack is used to hold operators and operands, and the top pieces of the Stack are used to carry out operations.
Advantages of Stack
1. Efficient use of the RAM
In comparison to other data structures, Stack makes better use of memory since it occupies a continuous block of memory.
2. Applied to Compiler Design
For parsing and programming language syntax analysis, stack data structures are utilized in compiler design.
3. Quick access period
When items are added to and removed from the top of the Stack, stack data structures offer quick access times for adding and deleting elements.
4. Simple to implement
Stack data structures are simple to comprehend and build, and they may be easily implemented using arrays or linked lists.
Disadvantages of Stack
1. Restricted Capacity
As it can only retain a certain amount of components, stack data structures have a restricted storage capacity. If the Stack is already full, adding more pieces might cause a stack overflow and cause data loss.
2. No arbitrary access
Stack data structures do not allow random access to their elements. Instead, they only allow adding and removing elements from the top of the stack. To access a middle-of-the-stack element, all the elements above it must be removed.
3. Not appropriate for some uses
Applications like searching or sorting algorithms that need to access components in the centre of the Stack are not suitable for stack data structures.
4. Limitations of the recursive function call
Recursive function calls are supported by the stack data structure, but too many of them might cause a stack overflow, which can cause the application to crash.
5. Underflow and overflow in a stack
The Stack data structure may experience stack overflow if an excessive number of components are placed onto it, and it may experience stack underflow if a disproportionate number of pieces are removed from it.
Also read - Data Structure MCQ
Frequently Asked Questions
What is the application of stack in real-time?
In real-time applications, stacks are used for managing function calls, memory allocation, expression evaluation, task scheduling, and more. They follow the Last-In-First-Out principle and are crucial for tasks like managing program flow, maintaining history, and implementing undo functionality.
What are the applications of stack memory?
Stack memory is like a special shelf for temporary things in a computer. It's used in many ways to keep track of what's happening. When you run a program, stack memory helps remember where you are and what you're doing. It's also used for storing small bits of information that programs need quickly. Think of it as a handy note-taking spot that helps the computer work smoothly.
What is a real-life example of a stack?
Imagine you're making a tower with different-sized blocks. You start by placing the biggest block at the bottom, then add smaller blocks on top of each other. When you want to take a block off, you start from the top and work your way down. This tower is like a stack in real life.
Conclusion
In this article, we have discussed various things about the stack such as the application of stack, its representation, operations as well as advantages and disadvantages.
To learn more, check out these articles:
If you want to learn more about stack and want to practice some questions which require you to take your basic knowledge on these topics a notch higher, then you can visit our Guided Path for Stack on Coding Ninjas Studio.
You can also consider our Mern Stack Course to give your career an edge over others.
Until then, All the best for your future endeavours, and Keep Coding.