Data Structure and Algorithm, Doubly Linked List, List

1. Doubly Linear Linked List
/***** @author: Er. Ganesh Ram Suwal *****/
/* Doubly Linked List */
#include<stdio.h>
#include<conio.h>
#include<alloc.h>
#include<process.h>
// Global variables
int data,position,i;
//Structure for Node
struct node
{
int info;
struct node *pnext,*pprev;
};
struct node *pthis, *pnew, *ptemp, *pfirst;
// Fubction Prototype
void nifb();
void nibxp();
void niaxp();
void nife();
void ndfb();
void ndfe();
void ndfsp();
void display();
void newNode()
{
pnew = (struct node*)malloc(sizeof(struct node));
printf("Data : ");
scanf("%d",&data);
pnew->info = data;
}
void invalidPosition()
{
printf("n****************************************************n");
printf(" Invalid Position! Try Again ");
printf("n****************************************************n");
}
// Counting the nodes of Linked List
int length()
{
int count = 0;
if(pfirst == NULL)
{
return 0;
}
else
{
pthis = pfirst;
count = 1;
while(pthis->pnext != NULL)
{
pthis = pthis->pnext;

2. Doubly Linear Linked List
count = count + 1;
}
return count;
}
}
// Main program function
void main()
{
clrscr();
int choice;
start:
printf("n********* Doubly Linked List *******************n");
printf("1: Node insertion from the beginingn");
printf("2: Node insertion from the endn");
printf("3: Node insertion before Xth positionn");
printf("4: Node insertion after Xth positionn");
printf("5: Node Delete from the begining n");
printf("6: Node Delete from the endn");
printf("7: Node delete from specified positionn");
printf("8: Displayn");
printf("9: Exitn");
printf("Enter your choice :");
scanf("%d",&choice);
switch(choice)
{
case 1:nifb();
break;
case 2:nife();
break;
case 3:nibxp();
break;
case 4:niaxp();
break;
case 5:ndfb();
break;
case 6:ndfe();
break;
case 7:ndfsp();
break;
case 8:display();
break;
case 9:exit(0);
break;
default: printf("Invalid Choice");
break;
}
goto start;
}
// Node Insertion from the begining
void nifb()
{
newNode();
pnew->pprev = NULL;
if(pfirst == NULL)
{
pnew->pnext = NULL;
pfirst = pnew;

3. Doubly Linear Linked List
}
else
{
pnew->pnext = pfirst;
pfirst = pnew;
}
}
//Node insertion before Xth position
void nibxp()
{
printf("position : ");
scanf("%d",&position);
if(position > length() || position < 1)
{
invalidPosition();
}
else if(position == 1)
{
nifb();
}
else
{
newNode();
if(pfirst == NULL)
{
pnew->pnext = NULL;
pnew->pprev = NULL;
pfirst = pnew;
}
else
{
pthis = pfirst;
for(i = 0;i<position-2;i++)
{
pthis = pthis->pnext;
}
ptemp = pthis->pnext;
pthis->pnext = pnew;
pnew->pnext = ptemp;
pnew->pprev = pthis;
}
}
}
//Node Insertion after Xth Position
void niaxp()
{
printf("position : ");
scanf("%d",&position);
if(position > length() || position < 1)
{
printf("n****************************************************n");
printf("Invalid Position! Try Again ");
printf("n****************************************************n");
}
else if(position == length())
{
nife();

4. Doubly Linear Linked List
}
else
{
newNode();
if(pfirst == NULL)
{
pnew->pnext = NULL;
pnew->pprev = NULL;
pfirst = pnew;
}
else
{
pthis = pfirst;
for(i = 0;i<position-1;i++)
{
pthis = pthis->pnext;
}
ptemp = pthis->pnext;
pthis->pnext = pnew;
pnew->pnext = ptemp;
pnew->pprev = pthis;
}
}
}
// Node Insertion from the end
void nife()
{
newNode();
pnew->pnext = NULL;
if(pfirst == NULL)
{
pnew->pprev = NULL;
pfirst = pnew;
}
else
{
pthis = pfirst;
while(pthis->pnext != NULL)
{
pthis = pthis->pnext;
}
pthis->pnext = pnew;
pnew->pprev = pthis;
}
}
//node delete from the begining
void ndfb()
{
if(pfirst == NULL)
{
printf("n==================================================n");
printf(" There is no node in the list");
printf("n==================================================n");
}
else
{

5. Doubly Linear Linked List
pthis = pfirst;
if(pfirst->pnext == NULL)
{
pfirst = NULL;
}
else
{
pfirst = pthis->pnext;
pfirst->pprev = NULL;
}
printf("n=================================================================n")
;
printf("The deleted element = %d",pthis->info);
printf("n=================================================================n")
;
free(pthis);
}
}
//node delete from the end
void ndfe()
{
if(pfirst == NULL)
{
printf("n==================================================n");
printf(" There is no node in the list");
printf("n==================================================n");
}
else
{
pthis = pfirst;
if(pfirst->pnext == NULL)
{
pfirst = NULL;
printf("n=================================================================n");
printf("The deleted element = %d",pthis->info);
printf("n=================================================================n");
free(pthis);
}
else
{
while(pthis->pnext->pnext != NULL)
{
pthis = pthis->pnext;
}
printf("n=================================================================n");
printf("The deleted node = %d",pthis->pnext->info);
printf("n=================================================================n");
free(pthis->pnext);
pthis->pnext = NULL;
}
}
}

6. Doubly Linear Linked List
//node delete from the specified position
void ndfsp()
{
if(pfirst == NULL)
{
printf("n==================================================n");
printf(" There is no node in the list");
printf("n==================================================n");
}
else
{
printf("Position : ");
scanf("%d",&position);
if(position > length() || position < 1)
{
invalidPosition();
}
else if(position == 1)
{
ndfb();
}
else if(position == length())
{
ndfe();
}
else
{
pthis = pfirst;
for(i=0;i<position-2;i++)
{
pthis=pthis->pnext;
}
ptemp = pthis->pnext->pnext;
printf("n=================================================================n");
printf("The deleted element = %d",pthis->pnext->info);
printf("n=================================================================n");
free(pthis->pnext);
pthis->pnext = ptemp;
pthis->pnext->pprev = pthis;
}
}
}
//Display function
void display()
{
int l;
l = length();
printf("n=================================================================n");
if(pfirst == NULL)
{
printf("There is no data in linked List");
}
else
{
printf("Node in DLL (Length=%d) : ",l);

7. Doubly Linear Linked List
pthis = pfirst;
printf("%d ",pthis->info);
while(pthis->pnext != NULL)
{
pthis = pthis->pnext;
printf("%d ",pthis->info);
}
}
printf("n=================================================================n");
}
OUTPUT

8. Doubly Linear Linked List

9. Doubly Linear Linked List