What Is the Concept of Stack in Data Structure?

What Is the Concept of Stack in Data Structure?

A stack is a fundamental data structure in computer science that follows the Last-In-First-Out (LIFO) principle. It is analogous to a stack of plates, where the last plate added is the first one to be removed. In a stack, elements are added and removed from only one end, known as the top.

Stack Operations:

A stack supports two primary operations:

• Push: Adds an element to the top of the stack.
• Pop: Removes and returns the topmost element from the stack.

Additionally, there are two more operations that can be performed on a stack:

• Peek: Returns the value of the topmost element without removing it.
• IsEmpty: Checks if the stack is empty or not.

Stack Implementation:

A stack can be implemented using various data structures, such as arrays or linked lists. Let’s consider an array-based implementation:

<pre>
<code>
class Stack {
    private int maxSize;
    private int[] stackArray;
    private int top;

    public Stack(int size) {
        maxSize = size;
        stackArray = new int[maxSize];
        top = -1;
    }

    public void push(int element) {
        if (top == maxSize - 1) {
            System.out.println("Stack overflow!");
            return;
        }
        stackArray[++top] = element;
    }

    public int pop() {
        if (isEmpty()) {
            System.println("Stack underflow!");
            return -1;
        }
        return stackArray[top--];
    }

    public int peek() {
        if (isEmpty()) {
            System.println("Stack is empty!");
            return -1;
        }
        return stackArray[top];
    }

    public boolean isEmpty() {
        return (top == -1);
    }
}
</code>
</pre>

Common Applications of Stacks:

Stacks find applications in various areas of computer science. Some common use cases include:

• Expression Evaluation: Stacks are used to evaluate arithmetic expressions, including infix, postfix, and prefix notations.
• Function Call Stack: The function call stack is a stack data structure that keeps track of function calls in a program. It is used for managing function invocations and returning to the calling functions.
• Undo/Redo Functionality: Stacks can be used to implement undo and redo functionality in text editors or graphic applications.
• Backtracking Algorithms: Many backtracking algorithms make use of stacks to store intermediate states and backtrack when necessary.
• Browser History: The browsing history in web browsers can be implemented using a stack. Each visited URL is pushed onto the stack, allowing users to navigate back by popping URLs from the stack.

In Conclusion:

The concept of a stack plays a vital role in computer science and programming. Understanding its operations and practical applications can greatly enhance your problem-solving abilities. Whether you’re working with algorithms, data structures, or software development in general, having a strong grasp of stacks will undoubtedly benefit you.