//////////////////////////////////////////////////////////////
//////////        -:   Singly Link list   :-        /////////
////////////////////////////////////////////////////////////
 
/* reference : Understandng pointer though c - Y karnetkar.
*/
 
//////////////////////////////////////////////////////////
//////////     Programmer : Harsh chandra     ///////////
////////////////////////////////////////////////////////
 
# include<stdio.h>
# include<conio.h>
# include<alloc.h>
# include<stdlib.h>
struct node
{  int data;
	struct node *link;
};
void append(struct node **,int);
void in_begin(struct node **,int);
void del(struct node **,int);
void in_middle(struct node **,int,int);
int count(struct node *);
void display(struct node *);
 
void main()
{   struct node *p;  /* p can be said as the head or a start ptr */
	 p=NULL;
	 /* Printing the menu */
	 int num,loc;
	 char choice;
	 do
	 { clrscr();
		printf("PROGRAM TO IMPLEMENT SINGLY LINKED LIST ");
		printf("\n=====================================");
		printf("\n\n1.Create \\ Appending The List");
		printf("\n2.Insert Node At Begining");
		printf("\n3.Insert Node In Middle");
		printf("\n4.Deleting a  Node");
		printf("\n5.Counting The No Of Nodes");
		printf("\n6.Displaying the list");
		printf("\n7.Exit");
		oper:
		gotoxy(1,15);printf("                                          ");
		gotoxy(1,11);printf("\n\nEnter ur Choice : ");
		choice=getch();
		switch(choice)
		{   case '1':
			  char ans;
			  do
			 {  printf("Enter any number : ");
				 scanf("%d",&num);
				 append(&p,num);
				 printf("Enter more (y/n) :");
				 fflush(stdin);
				 ans=getchar();
			  }while(ans !='n');
			 break;
			 case '2':
			 printf("Enter The Data : ");
			 scanf("%d",&num);
			 in_begin(&p,num);
			 break;
 
			 case '3':
			 printf("\nEnter The Position :");
			 scanf("%d",&loc);
			 printf("\nEnter The Data : ");
			 scanf("%d",&num);
			 in_middle(&p,loc,num);
			 break;
 
			 case '4':
			 printf("\nEnter The Data u Want To Delete : ");
			 scanf("%d",&num);
			 del(&p,num);
			 break;
 
			 case '5':
			 printf("\nThe No Of Nodes Are %d",count(p));
			 getch();
			 break;
 
			 case '6':
			 display(p);
			 getch();
			 break;
 
			 case '7':
			 printf("\n\nQuiting.......");
			 getch();
			 exit(0);
			 break;
 
			 default:
			 gotoxy(1,15);printf("Invalid choice.Please Enter Correct Choice");
			 getch();
			 goto oper;
 
		}
 
	 }while(choice !=7);
 
}
 
void append(struct node **q,int num)
{   struct node *temp,*r;
	 temp = *q;
	 if(*q==NULL)
	 {   temp = (struct node *)malloc(sizeof(struct node));
		  temp->data=num;
		  temp->link=NULL;
		  *q=temp;
	 }
	 else
	 {  temp = *q;
		 while(temp->link !=NULL)
		 {  temp=temp->link;
		 }
		 r = (struct node *)malloc(sizeof(struct node));
		 r->data=num;
		 r->link=NULL;
		 temp->link=r;
	 }
}
 
void display(struct node *q)
{     if(q==NULL)
		{  printf("\n\nEmpty Link List.Can't Display The Data");
			getch();
			goto last;
		}
		 while(q!=NULL)
	 {  printf("\n%d",q->data);
		 q=q->link;
	 }
	 last:
}
 
int count(struct node *q)
{  int c=0;
	if(q==NULL)
	{ printf("Empty Link List.\n");
	  getch();
	  goto last;
	}
	while(q!=NULL)
	{   c++;
		 q=q->link;
	}
	last:
	return c;
 
}
 
void in_begin(struct node **q,int num)
{  struct node *temp;
	if(*q==NULL)
	{  printf("Link List Is Empty.Can't Insert.");
		getch();
		goto last;
	}
	else
	{   temp=(struct node *)malloc(sizeof(struct node));
		 temp->data=num;
		 temp->link=*q;
		 *q=temp;  /* pointing to the first node */
	 }
	 last:
	 getch();
}
 
void in_middle(struct node **q,int loc,int num)
{  struct node *temp,*n;
	int c=1,flag=0;
	temp=*q;
	if(*q==NULL)
	{  printf("\n\nLink List Is Empty.Can't Insert.");
		getch();
		goto last;
	}
	else
	while(temp!=NULL)
	{  if(c==loc)
		{  n = (struct node *)malloc(sizeof(struct node));
			n->data=num;
			n->link=temp->link;
			temp->link=n;
			flag=1;
		}
		c++;
		temp=temp->link;
	 }
	 if(flag==0)
	 { printf("\n\nNode Specified Doesn't Exist.Cant Enter The Data");
		getch();
	 }
	 else
	 { printf("Data Inserted");
		getch();
	 }
	 last:
	 getch();
}
 
void del(struct node**q,int num)
{    if(*q==NULL)
	  {  printf("\n\nEmpty Linked List.Cant Delete The Data.");
		  getch();
		  goto last;
	  }
	  else
	  {
	  struct node *old,*temp;
	  int flag=0;
	  temp=*q;
	  while(temp!=NULL)
	  {  if(temp->data==num)
		  {   if(temp==*q)         /* First Node case */
				*q=temp->link;  /* shifted the header node */
				else
				old->link=temp->link;
 
				free(temp);
				flag=1;
			}
			else
			{  old=temp;
				temp=temp->link;
			}
		 }
		 if(flag==0)
			printf("\nData Not Found...");
		 else
			  printf("\nData Deleted...Tap a key to continue");
			  getch();
		}
		last:
		getch();
	  }