C++ : Lecture 15: Deletion from Any Position in Doubly Linked List : Mastering Linked List Made Simple !

 Mastering Linked List Made Simple: Your Easy Guide to Data Structures !

Deletion from Any Position in Doubly Linked List code [C++] :

#include<iostream>

using namespace std;

class Node{

    public:

    int data;

    Node* next;

    Node* prev;

    Node(int val){

        this->data = val;

        this->next = NULL;

        this->prev = NULL;

    }

};

int length(Node* head){

    Node* temp = head;

    int cnt = 1;

    while(temp->next != NULL){

        cnt++;

        temp = temp->next;

    }

    return cnt;

}

void insertAtBeg(Node* &head, Node* &tail, int data){

    // Step 1: Create a new Node

    Node* newNode = new Node(data);

    // Step 2: Handle empty list case

    if(head == NULL){

        head = newNode;

        tail = newNode;

        return;

    }

    // Step 3: Handle non-empty list case

    newNode->next = head;

    head->prev = newNode;

    head = newNode;

}

void delFromBeg(Node* &head, Node* &tail){

    // Step 1:Empty list case

    if(head == NULL){

        cout<<"List is empty";

        return;

    }

    // Step 2: Handle non empty list case

    head = head->next;

    head->prev->next = NULL;

    head->prev = NULL;

}

void delFromEnd(Node* &head, Node* &tail){

    // Step 1: Empty list

    if(head == NULL){

        cout<<"List is empty";

        return;

    }

    // Step 2: Non empty list

    tail = tail->prev;

    tail->next->prev = NULL;

    tail->next = NULL;

}

void delFromPos(Node* &head, Node* &tail, int pos){

    // Step 1: Handle empty list case

    if(head == NULL){

        cout<<"List is empty";

        return;

    }

    // Step 2: Handle non-empty list case

    // case 1: Deletion at beginning

    if(pos == 1){

        delFromBeg(head,tail);

        return;

    }

    // Case 2: Deletion from end

    int len = length(head);

    if(pos == len){

        delFromEnd(head,tail);

        return;

    }

    // Case 3: Any random position

    Node* back = NULL;

    Node* curr = head;

    int cnt = 1;

    while(cnt<pos){

        back = curr;

        curr = curr->next;

        cnt++;

    }

    back->next = curr->next;

    curr->next->prev = back;

    curr->prev = NULL;

    curr->next = NULL;

}

void print(Node* head, Node* tail){

    if(head == NULL){

        cout<<"List is empty."<<endl;

        return;

    }

    Node* temp = head;

    while(temp!=NULL){

        cout<<temp->data<<" ";

        temp=temp->next;

    }

    cout<<endl;

    cout<<"Head: "<<head->data<<endl;

    cout<<"Tail: "<<tail->data<<endl;

}

int main(){

    Node* head = NULL;

    Node* tail = NULL;

    insertAtBeg(head,tail,8);

    insertAtBeg(head,tail,7);

    insertAtBeg(head,tail,6);

    insertAtBeg(head,tail,5);

    insertAtBeg(head,tail,4);

    insertAtBeg(head,tail,3);

    insertAtBeg(head,tail,2);

    insertAtBeg(head,tail,1);

    delFromPos(head,tail,1);

    delFromPos(head,tail,7);

    delFromPos(head,tail,3);

    delFromPos(head,tail,4);

    print(head,tail);

    return 0;

}

Hey, thanks for watching our video about Linked list ! In this video we’ll walk you through:

- Concept

- Cases and subcases in deletion

- Dry run

- Code

All codes are available at my GitHub account, check them out here:

https://github.com/shyamkanth/Placements

Check out other videos from DS Revealed playlist: https://www.youtube.com/playlist?list=PLNXqJgOsTCZOB60T9HDhMf_o8RXbNWgqS

Check out our channel here: https://www.youtube.com/@DevelopersByte

Find us at: https://shyamkanth.github.io/

Timestamps:

0:00 Intro

0:36 Concept

2:27 Approach

3:03 Handling empty list case

3:42 Handling non-empty list case

5:25 Subcase 1: Deletion from beginning

6:20 Subcase 2: Deletion from end

8:25 Subcase 3: Deletion from any random position

22:50 Code

28:53 Output

30:50 Outro

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