Double Linked List

 

#include<iostream>

using namespace std;

class doubly_linked_list

{private:

struct node

{int element;

node* front;

node* rear;

}*head;

public:

doubly_linked_list();

void insertatbig(int element);

void insertatend(int element);

void  insertatkth(int element);

void insertatkthfromend(int  element);

void remove(int element);

void display();

bool isempty();

void swap(int i,int j);

~doubly_linked_list();

};

doubly_linked_list::doubly_linked_list()

{

  head=NULL;

}

bool doubly_linked_list::isempty()

{

  if(head==NULL)

  return true;

  else return false;

}

void doubly_linked_list::insertatbig(int element)

{

  if(isempty())

  {head=new node;

    head->element=element;

    head->front=NULL;

    head->rear=NULL;

    return;

  }

  node*t=new node();

  t->element=element;

  t->front=head;

  head->rear=t;

  t->rear=NULL;

  head=t;

  return;

 

}

void doubly_linked_list::insertatend(int element)

{

  if(isempty())

  {head=new node;

    head->element=element;

    head->front=NULL;

    head->rear=NULL;

    return;

  }

  node* t=new node;

  t->element=element;

  t->front=NULL;

  node*curr;

  curr=head;

  while(curr->front!=NULL)

  curr=curr->front;

  curr->front=t;

  t->rear=curr;

  return;

}

void doubly_linked_list::display()

{

if(isempty())

{

  cout<<"\n linked list iis empty\n";

  return;

}

node*curr=head;

while(curr!=NULL){

cout<<"\t"<<curr->element<<"->";

curr=curr->front;

}}

void doubly_linked_list::insertatkth(int pos)

{int count=0;

  node*curr=head;

  while(curr!=NULL)

  {

    count++;

    if(count==pos){

      node*t=new node;

    cout<<"\n enter the value of node to be inserted";

    int a;

    cin>>a;

    t->element=a;

    t->front=NULL;

    t->rear=NULL;

    if(curr->front!=NULL){

    t->front=curr->front;

    curr->front=t;

    curr->front->rear=t;

    t->rear=curr;}

    else{

    t->front=NULL;

    t->rear=curr;

    curr->front=t;}

    }

    curr=curr->front;

  }

}

void doubly_linked_list::remove(int element)

{node* curr=head;

if(isempty())

{

  cout<<"\n list is empty";

  return ;

 

}

  if(head->element==element)

  {

    node* t=head;

    head=head->front;

    head->rear=NULL;

    delete (t);return;

  }

  while(curr->front!=NULL)

  {if(curr->front->element==element)

  {if(curr->front->front==NULL){

    node*t=curr->front;

  curr->front=NULL;

  return;}

else if(curr->front->front!=NULL)  {

node*t=curr->front;

curr->front=t->front;

t->front->rear=curr;

delete(t);

return;}

 

  }

    curr=curr->front;

  }

}

doubly_linked_list::~doubly_linked_list()

{

 

}

int main()

{

  doubly_linked_list  dl;

dl.insertatend(5);dl.display();cout<<endl;

dl.insertatend(6);dl.display();cout<<endl;

dl.insertatend(7);dl.display();cout<<endl;

dl.insertatbig(8);dl.display();cout<<endl;

dl.insertatbig(9);dl.display();cout<<endl;

dl.insertatend(4);dl.display();cout<<endl;

dl.remove(6);dl.display();cout<<endl;

dl.remove(7);dl.display();cout<<endl;

dl.remove(9);dl.display();cout<<endl;

return 0;

}