Linked List in C

Linked List in C

Linked List ek important data structure hai jo DSA roadmap ka core part hai. Agar aap coding ya placements ki preparation kar rahe hain, to Linked List samajhna bahut zaroori hai. Ye ek linear data structure hai jahan elements memory me continuous nahi hote, balki nodes ke form me linked hote hain.

Array ke opposite, Linked List dynamic hoti hai aur memory efficiently use karti hai. Isi wajah se interviews aur real-world applications me iska use kaafi zyada hota hai.

Agar aap beginner hain, to pehle DSA Roadmap for Beginners follow karein jisse aapko poora learning path milega.

📌 What is Linked List?

Linked List ek collection hoti hai nodes ki. Har node me do parts hote hain:

1. Data

2. Pointer (Next)

Pointer next node ka address store karta hai, jisse nodes ek chain me connected rehte hain.

⚙️ Structure of Linked List

Node ka structure kuch aisa hota hai:

struct Node {

   int data;

   struct Node* next;

};

👉 Yaha “data” value store karta hai
👉 “next” next node ka address store karta hai

🔄 Types of Linked List

1. Singly Linked List

• Har node next node ko point karta hai

2. Doubly Linked List

• Har node previous aur next dono ko point karta hai

3. Circular Linked List

• Last node first node ko point karta hai

💡 Example (Simple Samajh)

Linked List:
10 → 20 → 30 → 40

👉 Har element next element se connected hai
👉 Last node ka next = NULL

💻 Linked List Implementation in C

#include <iostream>

using namespace std;

class Node {

public:

    int data;

    Node* next;

    Node(int val) {

        data = val;

        next = NULL;

    }

};

// Insert at Beginning

void insertAtBeginning(Node* &head, int val) {

    Node* newNode = new Node(val);

    newNode->next = head;

    head = newNode;

}

// Insert at End

void insertAtEnd(Node* &head, int val) {

    Node* newNode = new Node(val);

    if (head == NULL) {

        head = newNode;

        return;

    }

    Node* temp = head;

    while (temp->next != NULL) {

        temp = temp->next;

    }

    temp->next = newNode;

}

// Delete from Beginning

void deleteAtBeginning(Node* &head) {

    if (head == NULL) {

        cout << "List is empty\n";

        return;

    }

    Node* temp = head;

    head = head->next;

    delete temp;

}

// Delete by Value

void deleteByValue(Node* &head, int key) {

    if (head == NULL) return;

    // If head needs to be deleted

    if (head->data == key) {

        Node* temp = head;

        head = head->next;

        delete temp;

        return;

    }

    Node* temp = head;

    while (temp->next != NULL && temp->next->data != key) {

        temp = temp->next;

    }

    if (temp->next == NULL) {

        cout << "Value not found\n";

        return;

    }

    Node* nodeToDelete = temp->next;

    temp->next = temp->next->next;

    delete nodeToDelete;

}

// Search element

bool search(Node* head, int key) {

    Node* temp = head;

    while (temp != NULL) {

        if (temp->data == key)

            return true;

        temp = temp->next;

    }

    return false;

}

// Display Linked List

void display(Node* head) {

    Node* temp = head;

    while (temp != NULL) {

        cout << temp->data << " -> ";

        temp = temp->next;

    }

    cout << "NULL\n";

}

int main() {

    Node* head = NULL;

    // Insert elements

    insertAtBeginning(head, 5);

    insertAtEnd(head, 10);

    insertAtEnd(head, 20);

    insertAtEnd(head, 30);

    cout << "Linked List: ";

    display(head);

    // Delete operations

    deleteAtBeginning(head);

    cout << "After deleting first node: ";

    display(head);

    deleteByValue(head, 20);

    cout << "After deleting value 20: ";

    display(head);

    // Search

    if (search(head, 10))

        cout << "10 found in list\n";

    else

        cout << "10 not found\n";

    return 0;

}

👉 Ye basic structure aur traversal dikhata hai

⚙️ Basic Operations

1. Insertion

• Beginning me

• End me

• Middle me

2. Deletion

• First node

• Last node

• Specific node

3. Traversal

• List ko print karna

📈 Time Complexity

Operation                      Complexity

Insertion                          O(1)

Deletion                          O(1)

Search                            O(n)

👉 Linked List insertion aur deletion me fast hoti hai

🎯 Advantages of Linked List

• Dynamic size (fixed nahi hota)

• Memory efficient

• Easy insertion/deletion

❌ Disadvantages

• Random access possible nahi

• Pointer handling complex hota hai

• Extra memory required

🔥 Linked List vs Array

Feature                           Array                           Linked List

Memory                          Continuous                   Non-continuous

Size                                Fixed                             Dynamic

Access                           Fast                               Slow

🎯 Applications of Linked List

• Dynamic memory allocation

• Implementing stacks and queues

• Music playlist

• Browser history

💡 Common Mistakes

• NULL pointer handle na karna

• Memory allocation bhool jana

• Pointer galat link karna

👉 Tip: Diagram banake samjho

🚀 How to Master Linked List

1. Concept clear karo

2. Code likho (insert, delete)

3. Dry run karo

4. 15–20 questions solve karo

Agar aap Linked List seekh rahe hain to ye topics bhi zaroor padhein:

• 👉 DSA Roadmap for Beginners in Hindi

• 👉 Stack in Data Structure

• 👉 Recursion in C

• 👉 Binary Search in Data Structure

👉 Ye sab topics milkar aapki DSA strong banate hain

🏁 Conclusion

Linked List ek powerful data structure hai jo aapko dynamic data handling sikhata hai. Agar aap DSA roadmap follow kar rahe hain, to Linked List aapke liye next important step hai.

Practice aur concept clarity ke saath aap Linked List ko easily master kar sakte hain aur coding interviews ke liye ready ho sakte hain.

👉 Complete Roadmap:

https://sites.google.com/view/dsarop/

👉 Next Topic: Binary Search

https://sites.google.com/view/dsarop/binary-search