DOUBLY LINKED LIST – LINKED LIST IMPLEMENTATION

DOUBLY LINKED LIST – LINKED LIST IMPLEMENTATION

      Aim:

         To write a program to implement doubly linked list using linked list.

      Algorithm:

         Step 1: Declare header and pointer variables

         Step 2: Display the choices

         Step 3: If choice is 1 the get the element to be inserted in beginning and call ins_beg function.

         Step 4: If choice is 2 the get the element to be inserted in the end and call the ins_end function

         Step 5: If choice is 3 then get the element to be deleted and call deletion function.

         Step 6: If choice is 4 then call display duncation

         Step 7: If choice is default the exit the program

         Step 8: Terminate the program execution.

      Program:

       #include<stdio.h>

       #include<conio.h>

       #include<stdlib.h>

        void display(struct node *first);

       struct node

{

         int data;

         struct node *lptr,*rptr;

        }*head;

            struct node *ins_beg(int x,struct node *first)

{

         struct node *new1,*cur,*prev;

         new1=malloc(sizeof(struct node));

         if(first==NULL)

         {

                     new1->data=x;

                     new1->lptr=NULL;

                     new1->rptr=NULL;

                     return new1;

         }

         else

         {

                     new1->data=x;

                     new1->lptr=NULL;

                     new1->rptr=first;

                     return new1;

         }

}

         struct node *ins_end(int x,struct node *first)

{

         struct node *new1,*cur,*prev;

         new1=malloc(sizeof(struct node));

         if(first==NULL)

         {

                     new1->data=x;

                     new1->lptr=NULL;

                     new1->rptr=NULL;

                     return new1;

         }

         else

         {

                     cur=first;

                     while(cur->rptr!=NULL)

                     {

                                 prev=cur;

                                 cur=cur->rptr;

                     }

                     cur->rptr=new1;

                     new1->data=x;

                     new1->lptr=cur;

                     new1->rptr=NULL;

                     return first;

         }

}

       struct node *deletion(struct node *first,int del)

{

         struct node *prev,*cur;

         cur=first;

         if(first==NULL)

         {

                     printf("\n\nNo data present!!!");

                     getch();

         }

         else if(first->data==del)

         {

                     printf("\n\nData %d is deleted",first->data);

                     first=first->rptr;

                     getch();

                     return first;

         }

         else

         {

                     while(cur->rptr!=NULL && cur->data!=del)

                     {

                                 prev=cur;

                                 cur=cur->rptr;

                     }

                     if(cur->rptr==NULL && cur->data!=del)

                                 printf("\n\nData is not present!!!");

                     else if(cur->rptr!=NULL && cur->data==del)

                     {

                                 prev->rptr=cur->rptr;

                                 (cur->rptr)->lptr=prev;

                                 printf("\n\nData % d is deleted",cur->data);

                     }

                     else if(cur->rptr==NULL && cur->data==del)

                     {

                                 prev->rptr=NULL;

                                 printf("\n\nData %d is deleted:",cur->data);

                     }

                     getch();

                     return first;

         }

}

      void main()

{

         int x,ch,del;

         head=NULL;

         clrscr();

         printf("\n1.Insert in Begining\n2.Insert in the End\n3.Delete\n4.Display");

         while(1)

         {

                     printf("\n\nEnter your Choice :: ");

                     scanf("%d",&ch);

                     switch(ch)

                     {

                                 case 1:

                                             printf("\n\nEnter the element to be inserted::");

                                             scanf("%d",&x);

                                             head=ins_beg(x,head);

                                             break;

                                 case 2:

                                             printf("\n\nEnter the element to be inserted::");

                                             scanf("%d",&x);

                                             head=ins_end(x,head);

                                             break;

                                 case 3:

                                             printf("\n\nEnter the element to be deleted::");

                                             scanf("%d",&del);

                                             head=deletion(head,del);

                                             break;

                                 case 4:

                                             display(head);

                                             break;

                                 default:

                                             printf("\n\nInvalid Choice......");

                                             getch();

                                             exit(0);

                     }

         }

}

      void display(struct node *first)

{

         struct node *temp;

         temp=first;

         if(temp==NULL)

                     printf("\n\nList is empty!!!");

         while(temp!=NULL)

         {

                     printf("%d ->",temp->data);

                     temp=temp->rptr;

         }

         getch();

}

      Output:

      1.Insert in Begining

      2.Insert in the End

      3.Delete

      4.Display

Enter your Choice :: 1

Enter the element to be inserted::2

Enter your Choice :: 1

Enter the element to be inserted::3

Enter your Choice :: 4

3 ->2 ->

Enter your Choice :: 2

Enter the element to be inserted::1

Enter your Choice :: 2

Enter the element to be inserted::5

Enter your Choice :: 4

3 ->2 ->1 ->5 ->

Enter your Choice :: 3

Enter the element to be deleted::1

Data  1 is deleted

Enter your Choice :: 4

3 ->2 ->5 ->