Arrays

Introduction to Stacks

A Stack is a linear data structure that follows LIFO (Last In, First Out) principle. Think of it like a stack of plates—you add/remove from the top.

Key Properties

• Insertion (push) and deletion (pop) happen at the top.
• Access only the top element.
• Used in: function calls, undo operations, expression evaluation, etc.

Example in C++

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

int main() {
    stack <int> s;
    s.push(10);
    s.push(20);
    s.push(30);

    cout << "Top: " << s.top() << endl;  // 30
    s.pop();  // removes 30

    cout << "New Top: " << s.top() << endl;  // 20
    return 0;
}

    

Learning resource

Readings Stacks
Videos Stacks

Introduction to Queues

A Queue is a linear data structure that follows FIFO (First In, First Out) principle. Think of it like a line at a ticket counter—first come, first served.

Key Properties

• Insertion (enqueue) at the rear.
• Deletion (dequeue) from the front.
• Used in: scheduling, buffering, BFS (graphs), etc.

Example in C++

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

int main() {
    queue<int> q;
    q.push(100);
    q.push(200);
    q.push(300);

    cout << "Front: " << q.front() << endl;  // 100
    q.pop();  // removes 100

    cout << "New Front: " << q.front() << endl;  // 200
    return 0;
}

    

Learning resource

Readings Queues
Videos Queues