🔗 Linked Lists: A Beginner’s Guide to DSA

📌 Introduction

In the world of data structures, Linked Lists are foundational. They provide flexibility in memory management and are key to implementing complex structures like stacks, queues, and graphs.

This guide gives you a beginner-friendly overview of what a linked list is, how it works, and how you can implement one in your own code.

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🔍 What is a Linked List?

A Linked List is a linear data structure where each element (node) contains two parts:

1. Data: The value or content.

2. Pointer (Next): A reference to the next node in the sequence.

Unlike arrays, linked lists are not stored in contiguous memory locations.

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⚙️ Why Use Linked Lists?

• 📌 Dynamic Size

• 🔄 Easy Insertion/Deletion (No shifting of elements)

• 📂 Used in memory management and dynamic structures

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🧠 Types of Linked Lists

1. Singly Linked List – Each node points to the next node.

2. Doubly Linked List – Nodes point to both the previous and next nodes.

3. Circular Linked List – Last node points back to the first node (can be singly or doubly).

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💡 Key Terminology

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💻 Sample Code (Singly Linked List in C++)

#include <iostream>
using namespace std;

class Node {
public:
    int data;
    Node* next;

    Node(int value) {
        data = value;
        next = nullptr;
    }
};

void printList(Node* head) {
    while (head != nullptr) {
        cout << head->data << " -> ";
        head = head->next;
    }
    cout << "NULL" << endl;
}

int main() {
    Node* head = new Node(10);
    head->next = new Node(20);
    head->next->next = new Node(30);

    printList(head);
    return 0;
}

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📈 Applications of Linked Lists

• Dynamic memory allocation

• Implementing stacks and queues

• Hash Tables (Chaining)

• Representing graphs (adjacency list)

• Navigation systems (Previous/Next)

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⚠️ Limitations of Linked Lists

• Higher memory usage (due to pointers)

• Sequential access (no direct indexing)

• Complex traversal (especially in reverse)

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🎯 Practice Ideas

• Insert at beginning, middle, end

• Delete from beginning, middle, end

• Reverse a linked list

• Detect cycle in a linked list

• Merge two sorted linked lists

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✅ Conclusion

Understanding linked lists is crucial for solving real-world problems and cracking technical interviews. Start small, visualize it, code it — and soon you’ll master this flexible data structure.

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Article 2: Doubly Linked Lists Explained