Linked List

Getnode()//creates  node
1.	[allocate memory for node] Set temp:=(node *)malloc(sizeof(node));
2.	If (temp==NULL) then:  return “error” and exit
3.	Else return temp;
4.	Exit
Insert_beg(x)//inserts element  x at beginning of list
1.	Call getnode();
2.	[store value in newly created node] Set temp-gt;data := x and temp-gt;next := NULL;
3.	If start==NULL then: Set start := temp;
4.	Else 
a.	Set  temp-gt;next := start;
b.	Set start  := temp;
5.	Exit
Insert_end(x)//inserts x at the end of the list
1.	Call getnode();
2.	[store value in newly created node] Set temp-gt;data := x and temp-gt;next := NULL;
3.	If start==NULL then: Set start := temp;
4.	Else 
a.	Set  ptr:=start;
b.	Repeat  step c and d while ptr!=NULL
c.	Set save := ptr;
d.	Set  ptr:= ptr-gt;next;
e.	Set save-gt;next:= temp;
5.	Exit
Insert_mid(index,x)//Inserts  node with value x after  index no. of  nodes
1.	[initialize ct] ct := 0;
2.	Call getnode();
3.	[store value in newly created node] Set temp-gt;data := x and temp-gt;next := NULL;
4.	 Set ptr:= start;
5.	Repeat while(ctlt;index)
a.	Set save := ptr;
b.	Set ptr := ptr -gt; next;
c.	[increment ct] ct++;
6.	If start==NULL then: set start :=temp;
7.	Else if (ptr==start)
a.	Set temp-gt;next := ptr;
b.	Set start  :=  temp;
8.	Else 
a.	Set temp-gt;next := save-gt;next;
b.	Save-gt;next := temp;
9.	exit
reverse()//reverses the given linked list
1.	Set  ptr := save := start;
2.	If  (start==NULL) then print “list is empty”;
3.	Else
a.	Set save := NULL
b.	Repeat steps c,d and e while (ptr!=NULL)
c.	Set  temp := save;
d.	Set save := ptr and save-gt;next:= temp;
e.	Set ptr := ptr-gt;next;
f.	Set start := save;
4.	Exit
Delete_node(v)//deletes node with value v from list
1.	Set ptr := start;
2.	If start := NULL then print “list is empty”;
3.	Else
a.	Repeat while ((ptr != NULL ) && (ptr-gt;data != v))
b.	Set save := ptr;
c.	Set ptr := ptr -gt; next;
d.	[end of while]
e.	Repeat steps  f,g,and h if(ptr-gt;data == v) then:
f.	If ptr==start  then:
i.	Set del := ptr-gt;data and ptr := ptr-gt;next;
ii.	Free(start);
iii.	Set start := ptr;
g.	Else
i.	Set del:=ptr-gt;data and save-gt;next := ptr-gt;next;
ii.	Free ptr;
h.	Return del;
4.	Else print “Element to be deleted not found” and exit;
5.	[End]
Search(v)//searches element v in list
1.	Initialize ptr := start;
2.	If start == NULL  then : print “list is empty”;
3.	Else
a.	Do ptr := ptr-gt;next,  while (ptr !=NULL  && ptr-gt;data !=v) 
b.	If ptr-gt;data == v then return ptr;
c.	Else print “Element not found”;
4.	[End]
Count()//counts number of nodes in the list
1.	Initialize ct := 0 and ptr := start;
2.	Repeat  step 3 while (ptr!=NULL)
3.	[increase ct] ct++ and set ptr := ptr-gt;next;
4.	Return ct and exit;

//Implement Linked List (All Basic operations)

#include<stdio.h>
#include<conio.h>
#define null 0

struct node
{
int data;
struct node *next;
};
typedef struct node Node;
Node *start=null;


int main()
{
int d,k,a,b,count;
char ch;
Node *n,*ptr,*prev,*pprev,*start1=null;
while(1)
{
k=showlist();
if(k==1)
{
	while(1)
	{
	printf("Enter data ");
	scanf("%d",&d);
	n=(Node *)malloc(sizeof(Node));
	n->data=d;
	n->next=start;
	start=n;
	printf("want to enter more data (y or n) ");
	fflush(stdin);
	scanf("%c",&ch);
	if(ch=='n')
	break;
	}
}
else if(k==2)
{
	while(1)
	{
	printf("Enter data ");
	scanf("%d",&d);
	n=(Node *)malloc(sizeof(Node));
	n->data=d;
	n->next=null;
	if(start!=null)
	{
		ptr=start;
		while(ptr!=null)
		{
		prev=ptr;
		ptr=ptr->next;
		}
		prev->next=n;
	}
	else
	{
		start=n;
	}
	printf("want to enter more data (y or n) ");
	fflush(stdin);
	scanf("%c",&ch);
	if(ch=='n')
	break;
}
}
else if(k==3)
{
	printf("Enter data ");
	scanf("%d",&d);
	n=(Node *)malloc(sizeof(Node));
	n->data=d;
	printf("Before what element you want to insert ");
	scanf("%d",&b);
	ptr=start;
	prev=start;
	count=0;
	while(ptr!=null)
	{
		if(ptr->data==b&&count==0)
		{
		   n->next=start;
		   start=n;
		   printf("Insert Successfully ");
		   goto l2;
		}
		else if(ptr->data==b)
		{
		prev->next=n;
		n->next=ptr;
		 printf("Insert Successfully ");
		goto l2;
		}
	prev=ptr;
	ptr=ptr->next;
	count++;
	}
  l2:	if(ptr==null)
	{
	printf("Data not found");
	}
}
else if(k==4)
{
	printf("Enter data ");
	scanf("%d",&d);
	n=(Node *)malloc(sizeof(Node));
	n->data=d;
	printf("After what element you want to insert ");
	scanf("%d",&a);
	ptr=start;
	while(ptr!=null)
	{
	prev=ptr;
		if(ptr->data==a)
		{
		   n->next=ptr->next;
		   prev->next=n;
		   printf("Insert Successfully ");
		   goto l3;
		}
	ptr=ptr->next;
	}
  l3:	if(ptr==null)
	{
	printf("Data not found");
	}
}
else if(k==5)
{
	count=0;
	ptr=start;
	while(ptr!=null)
	{
		count++;
		ptr=ptr->next;
	}
	printf("\nTotal no. of nodes in LList is : %d",count);
}
else if(k==6)
{
	if(start==null)
	printf("Delete unsuccessful becoz LList is empty");
	else
	{
	ptr=start;
	count=ptr->data;
	start=start->next;
	printf("First node that is %d deleted successfully",count);
	}
}
else if(k==7)
{
	if(start==null)
	printf("Delete unsuccessful becoz LList is empty");
	else
	{
	ptr=start;
	while(ptr->next!=null)
	{
	prev=ptr;
	ptr=ptr->next;
	}
	prev->next=null;
	printf("Last node that is %d deleted successfully",ptr->data);
	}
}
else if(k==8)
{
	if(start==null)
	printf("Delete unsuccessful becoz LList is empty");
	else
	{
	printf("Before what node u want to delete ");
	scanf("%d",&b);
	pprev=null;
	ptr=start;
	prev=start;
	count=0;
	while(ptr!=null)
	{
	if(ptr->data==b&&count==0)
	{
	printf("no delete");
	goto l4;
	}
	else if(ptr->data==b&&count==1)
	{
	start=ptr;
	printf("Delete");
	goto l4;
	}
	else if(ptr->data==b)
	{
	prev->next=ptr;
	printf("Delete");
	goto l4;
	}
	else
	{
	pprev=prev;
	prev=ptr;
	ptr=ptr->next;
	count++;
	}
	}
 l4:	}
}
else if(k==9)
{
	if(start==null)
	printf("Delete unsuccessful becoz LList is empty");
	else
	{
	printf("After what node u want to delete ");
	scanf("%d",&a);
	ptr=start;
	prev=null;
	pprev=null;
	count=0;
	while(ptr!=null)
	{
	pprev=ptr->next;
	if(ptr->data==a&&count==0)
	{
	ptr->next=pprev->next;
	printf("Node deleted successfully ");
	goto l5;
	}
	else if(ptr->data==a)
	{
	ptr->next=pprev->next;
	printf("Node deleted successfully ");
	goto l5;
	}
	else
	{
	prev=ptr;
	ptr=ptr->next;
	count++;
	}
	}
  l5:	}
}
else if(k==10)
{
	printf("From what element you want to split L.List ");
	scanf("%d",&a);
	ptr=start;
	while(ptr!=null&&ptr->data!=a)
	{
	ptr=ptr->next;
	}
	prev=ptr->next;
	ptr->next=null;
	start1=prev;
 l6:	printf("\nElements of First LL are : ");
	ptr=start;
	while(ptr!=null)
	{
	printf("%d ->",ptr->data);
	ptr=ptr->next;
	}
	printf("/");
	printf("\nElements of Second LL are : ");
	ptr=start1;
	while(ptr!=null)
	{
	printf("%d ->",ptr->data);
	ptr=ptr->next;
	}
	printf("/");
}
else if(k==11)
{
	ptr=start;
	while(ptr!=null)
	{
	prev=ptr;
	ptr=ptr->next;
	}
	prev->next=start1;
	start1=null;
	goto l7;
}
else if(k==12)
{
	if(start1==null)
	{
  l7:	printf("\nElements of LL are : ");
	ptr=start;
	while(ptr!=null)
	{
	printf("%d ->",ptr->data);
	ptr=ptr->next;
	}
	printf("/");
	}
	else
	goto l6;
	getch();
}
else
exit(0);
}
}

int showlist()
{
	int k;
	printf("\nChoose your option :\n ");
	printf("1. Insert in the begining\n ");
	printf("2. Insert in the end\n ");
	printf("3. Insert before any data\n ");
	printf("4. Insert after any data\n ");
	printf("5. Count the no. of nodes\n ");
	printf("6. Delete the first node\n ");
	printf("7. Delete the last node\n ");
	printf("8. Delete before any node\n ");
	printf("9. Delete after any node\n ");
	printf("10. Split the L.List\n ");
	printf("11. Merge the L.List\n ");
	printf("12. Show Content of L. List \n ");
	printf("13. Exit\n");
	printf("Enter choice : ");
	scanf("%d",&k);
	return k;
}