Deque Data Structure in JavaScript 🚀

A simple implementation of the Deque (Double-Ended Queue) data structure in JavaScript. This repository demonstrates how to create a deque class with essential methods and explains its functionality with practical examples.

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What is a Deque?

A Deque (Double-Ended Queue) is a linear data structure that allows elements to be added or removed from both ends—front and back. It is a generalization of a queue, where elements can be inserted or removed from either end, making it more versatile than a standard queue.

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Features

• InsertFront: Add an element to the front of the deque.
• InsertBack: Add an element to the back of the deque.
• RemoveFront: Remove and return the element from the front.
• RemoveBack: Remove and return the element from the back.
• PeekFront: View the element at the front without removing it.
• PeekBack: View the element at the back without removing it.
• Size: Get the number of elements in the deque.
• isEmpty: Check if the deque is empty.

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Code Implementation

Here’s the JavaScript implementation of the deque:

class Deque {
    constructor() {
        this.items = [];
    }

    // Add an element to the front of the deque
    insertFront(element) {
        this.items.unshift(element);
    }

    // Add an element to the back of the deque
    insertBack(element) {
        this.items.push(element);
    }

    // Remove and return the element from the front of the deque
    removeFront() {
        if (this.isEmpty()) {
            return "Deque is empty!";
        }
        return this.items.shift();
    }

    // Remove and return the element from the back of the deque
    removeBack() {
        if (this.isEmpty()) {
            return "Deque is empty!";
        }
        return this.items.pop();
    }

    // Peek at the element at the front without removing it
    peekFront() {
        if (this.isEmpty()) {
            return "Deque is empty!";
        }
        return this.items[0];
    }

    // Peek at the element at the back without removing it
    peekBack() {
        if (this.isEmpty()) {
            return "Deque is empty!";
        }
        return this.items[this.items.length - 1];
    }

    // Get the size of the deque
    size() {
        return this.items.length;
    }

    // Check if the deque is empty
    isEmpty() {
        return this.items.length === 0;
    }
}

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Example Usage

// Initialize the deque
const deque = new Deque();

// Insert elements at the front and back
deque.insertFront(10);
deque.insertBack(20);
deque.insertFront(5);

// Peek at the front and back elements
console.log(deque.peekFront()); // Output: 5
console.log(deque.peekBack());  // Output: 20

// Remove elements from the front and back
console.log(deque.removeFront()); // Output: 5
console.log(deque.removeBack());  // Output: 20

// Get the size of the deque
console.log(deque.size()); // Output: 1

// Check if the deque is empty
console.log(deque.isEmpty()); // Output: false

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Real-World Applications

1. Task Scheduling: Used in round-robin scheduling for managing tasks.
2. Sliding Window Algorithms: Efficiently processing a range of elements in an array or list.
3. Palindrome Checker: Checking if a string is a palindrome by comparing characters from both ends.
4. Deque-based Buffer: Implementing a buffer where data can be inserted and removed from both ends.

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TikTok Tutorial 🎥

Want to see a quick tutorial on how to build this? Check out this TikTok video:

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How to Run the Code

1. Clone the repository:

   git clone https://github.com/fix2015/structure_deque
   cd structure_deque

2. Open the file index.js in your favorite code editor.
3. Run the file using Node.js:

   node index.js

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Contributing

Contributions are welcome! If you have suggestions or want to add new features, feel free to create a pull request.

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License

This project is licensed under the MIT License.

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