Introduction
Data structures form the backbone of efficient algorithms, enabling organized data storage and retrieval. Among the most fundamental data structures are the stack and queue, each designed for specific use cases with distinct data management methods.
What is a Stack?
A stack is a linear data structure that operates on the Last In, First Out (LIFO) principle. This means that the last element added to the stack is the first to be removed. Stacks are commonly compared to a stack of plates – the last plate placed on top is the first one to be taken off.
Basic Operations:
Push: Add an element to the top of the stack.
Pop: Remove the top element from the stack.
Peek/Top: View the top element without removing it.
Example in 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; // 20
s.pop();
cout << "Top element after pop: " << s.top() << endl; // 10
return 0;
}What is a Queue?
A queue is another linear data structure but it follows the First In, First Out (FIFO) principle. Imagine people standing in line; the first person in line is the first to be served.
Basic Operations:
Enqueue: Add an element to the end of the queue.
Dequeue: Remove an element from the front of the queue.
Front: View the front element without removing it.
Rear: View the last element.
Example in C++:
#include<iostream>
#include<queue>
using namespace std;
int main() {
queue<int> q;
q.push(10);
q.push(20);
cout << "Front element: " << q.front() << endl; // 10
q.pop();
cout << "Front element after dequeue: " << q.front() << endl; // 20
return 0;
}Comparison Between Stack and Queue
Stack: LIFO (Last In, First Out) – Used when the most recent item is required first.
Queue: FIFO (First In, First Out) – Used when the first item added must be processed first.
Applications of Stack and Queue
Stack: Used in function call management, undo operations in text editors, and expression evaluation.
Queue: Used in printer task scheduling, customer service systems, and breadth-first search algorithms.
Conclusion
Understanding stack and queue is essential for organizing and managing data effectively in various programming scenarios. These data structures are critical in both basic and advanced algorithm designs.
Also Read - Stack in Data Structure
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