Algorithm to insert a node at the beginning of single linked list:
Let head be a pointer that stores the address of first node
step 1: Read the value to inserted into linked list
step 2: create a new node using
malloc function
step 3: Assign the value read to
the data field of newnode (newnode -> data =value)
step 4: set the next of newnode to
head (newnode ->next = head)
step 5: set the head pointer to
newnode (head = newnode)
Algorithm to insert a node at the end of single linked list:
Let head be a pointer that stores the address of first node
step 1: Read the value to inserted into linked list
step 2: create a new node using
malloc function
step 3: Assign the value read to
the data field of newnode
step 4: if there is no linked list
then newnode becomes first node
step 5: otherwise go to the
lastnode in linked list
Step
5.1: attach newnode to last node (lastnode ->next = newnode)
Step
5.2: newnode->next = NULL
Algorithm to insert a node at a given position of single linked
list:
Let head be a pointer that stores the address of first node
step 1: Read the value to
inserted into linked list and the position at which newnode has to be inserted
step 2: create a new node using
malloc function
step 3: Assign the value read to
the data field of newnode
step 4: store the node before the
given position in a pointer c
step 5: newnode->next =
c->next
step 6: c->next = newnode
Algorithm to delete a node at the beginning of single linked list:
Let head be a pointer that stores the address of first node
step 1: If there is no linked list then print Linked list is
empty
step 2: If linked list exists
step
2.1: delete the first node
step
2.2: second node becomes first node
Algorithm to delete a node at the end of single linked list:
Let head be a pointer that stores the address of first node
step 1: If there is no linked list then print Linked list is
empty
step 2: If linked list exists
step
2.1: move to last but one node and store the address of last but one node in
pointer c
step
2.2: store the address of last node in pointer p and detele the last node
(free(p))
step
2.3: c->next = NULL
Algorithm to delete a node at given position of single linked list:
Let head be a pointer that stores the address of first node
step 1: If there is no linked list then print Linked list is
empty
step 2: If linked list exists
step
2.1: Read the position at which the node has to deleted
step
2.2: Store the address of node before the to be deleted node in pointer c
step
2.3: c->next = c->next->next
step 2.4: delete the node at given position
step 2.4: delete the node at given position
Algorithm to display the elements of single linked list
Let head be a pointer that stores the address of first node
step 1: If there is no linked list then print Linked list is
empty
step 2: If linked list exists store the address of first node in pointer c ( c = head)
step 2: If linked list exists store the address of first node in pointer c ( c = head)
step
2.1: print the data field in c (print c->data)
step
2.2 move c to store the address of next node ( c = c-> next)
step 3: go to step 2 until c is not equal to NULL
Program
#include <stdio.h>
#include <stdlib.h>
struct node
{
int data;
struct node *next;
};
struct node *head =NULL,*c,*p;
create()
{
int value;
printf("enter
the value ");
scanf("%d",&value);
struct node *new =
(struct node *)malloc(sizeof(struct node));
new->data=value;
new->next=NULL;
if(head == NULL)
{
head=new;
}
else
{
c=head;
while(c->next
!= NULL)
{
c=c->next;
}
c->next=new;
}
}
insertbeg(int value)
{
struct node *new =
(struct node *)malloc(sizeof(struct node));
new->data=value;
new->next=head;
head = new;
}
insertend(int value)
{
struct node *new =
(struct node *)malloc(sizeof(struct node));
new->data=value;
c=head;
while(c->next !=
NULL)
{
c=c->next;
}
c->next=new;
new->next=NULL;
}
insertmiddle(int value)
{
int pos;
printf("enter
the position at which new node has to be inserted");
scanf("%d",&pos);
struct node *new =
(struct node *)malloc(sizeof(struct node));
new->data=value;
c=head;
int i=1;
while(i<pos)
{
p=c;
c=c->next;
i++;
}
new->next=c;
p->next=new;
}
deletebeg()
{
p=head;
head=head->next;
free(p);
}
deletemiddle()
{
int pos, i=1;
printf("enter
the position of the node that has to be deleted");
scanf("%d",&pos);
c=head;
while(i<pos)
{
p=c;
c=c->next;
i++;
}
p->next=c->next;
free(c);
}
deleteend()
{
c=head;
while(c->next !=
NULL)
{
p=c;
c=c->next;
}
free(p->next);
p->next=NULL;
}
display()
{
if(head == NULL)
printf("list
is empty");
else
{
c=head;
while(c->next
!=NULL)
{
printf("%d
-> ",c->data);
c=c->next;
}
printf("%d\n",c->data);
}
}
main()
{
int
choice,option,value;
while(1)
{
printf("Press
1. Create\n 2. Insert \n 3. Delete \n 4.
Display\n 5. Exit \n");
printf("enter
ur choice");
scanf("%d",&choice);
switch(choice)
{
case
1: create();
break;
case
2:
if(head != NULL)
{
option=0;
while(option
!= 4)
{
printf("Press
1. insert as first node \n 2. insert as
middle node \n 3. insert as last node \n
4. go to main menu\n");
printf("enter
ur choice\n");
scanf("%d",&option);
if(option
!= 4)
{
printf("enter
the value ");
scanf("%d",&value);
}
switch(option)
{
case
1: insertbeg(value);
display();
break;
case
2: insertmiddle(value);
display();
break;
case
3: insertend(value);
display();
break;
case
4: break;
default:
printf("invalid choice\n");
}
}
}
else
printf("list
is empty");
break;
case
3:
option=0;
if(head
!= NULL)
{
while(option
!= 4)
{
printf("Press
1. delete first node \n 2. delete middle
node \n 3. Delete last node \n 4. go to
main menu\n");
printf("enter
ur choice\n");
scanf("%d",&option);
switch(option)
{
case
1: deletebeg();
display();
break;
case
2: deletemiddle();
display();
break;
case
3: deleteend();
display();
break;
case
4: break;
default:
printf("invalid choice\n");
}
}
}
else
printf("list
is empty and cannot be deleted");
break;
case
4: display();
break;
case
5: exit(0);
default:
printf("invalid choice");
}
}
}
