Insertion in Stack: A Complete Guide for Beginners

By
Nidhi Goswami
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0
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Insertion in stack

Stacks are one of the most fundamental data structures in computer science. Whether you are preparing for coding interviews or learning data structures and algorithms and understanding how insertion in stack works is crucial. In this blog, we will dive deep into what stack insertion means, how it works, and how you can implement it in popular programming languages like Python, C++, and Java.

insertion in stack

What is a Stack?

A stack is a simple but powerful linear data structure that follows the Last In First Out (LIFO) structure. This means that the most recently added element is the first one to be removed just like stacking plates where you add new plates on top and remove the top one first. In programming stacks are widely used in scenarios like undo-redo functionality, expression evaluation, and function call tracking. Understanding how a stack works is essential before learning operations like insertion in stack which involves adding elements to the top of the stack using the push operation.

What is insertion in stack?

Insertion in stack is also called the push operation that means adding a new element to the top of the stack. Stacks follow the Last In First Out (LIFO) rule so the most recent element added is the first one removed. The push operation helps you grow the stack by placing new items on top. Most programming languages offer a built in method to push elements but you can also write your own version using arrays or linked lists. This simple operation is key to how stacks work in real world programs.

Insertion in Stack (Algorithm)

To insert an element into a stack then follow these steps:

  1. Check if the stack is full
    If you are using a fixed size stack like an array then make sure there is a space to add a new element. If the stack is full then keep display an overflow error.
  2. Increase the top pointer
    Move the top pointer to the next position to make room for the new element.
  3. Insert the new element
    Place the element at the position pointed to by the top.

Code Examples for Insertion in Stack

Insertion in Stack using Python

stack = []

def push(element):
    stack.append(element)
    print(f"Inserted {element} into stack.")

push(10)
push(20)
print("Current Stack:", stack)

Insertion in Stack using C++

#include <iostream>
#include <stack>
using namespace std;

int main() {
    stack<int> s;
    s.push(10);
    s.push(20);
    cout << "Top element: " << s.top() << endl;
    return 0;
}

Insertion in a Stack using Java

import java.util.Stack;

public class StackExample {
    public static void main(String[] args) {
        Stack<Integer> stack = new Stack<>();
        stack.push(10);
        stack.push(20);
        System.out.println("Top element: " + stack.peek());
    }
}

Applications of Stack Insertion

  • Parsing expressions
  • Backtracking algorithms
  • Function call management in recursion
  • Undo-redo functionality

Frequently Asked Questions (FAQs)

What is insertion in stack?

Insertion in stack refers to adding a new element at the top of the stack also called the push operation.

What is the time complexity of insertion in a stack?

The time complexity is O(1) which is a constant time.

Can we insert elements at the bottom of the stack?

Not directly. Stacks only allow insertion and deletion from the top.