1. LINKED LIST

2. 1 2 Insert node at the beginning struct node { int data;
struct node *next;
}*head,*var,*trav;
head=NULL;
head
Insert node at the beginning 1
var=(struct node *)malloc(sizeof (struct node));
var->data=value;
if(head==NULL) {
head=var;
head->next=NULL; }
else
var->next=head; 10
var
1000 10
head
1000 2
NULL

3. 5 3 4 Insert node at the beginning10
head
1000 20
head
2000 5
NULL
1000 10
1000
NULL
Insert node at the beginning 3
var=(struct node *)malloc(sizeof (struct node));
var->data=value;
if(head==NULL) {
head=var;
head->next=NULL; }
else
var->next=head; 20
var
2000 4 20
var
2000
1000

4. 6 1 2 3 4 4 5 Insert node at the End 20 head 2000 1000 10 1000 NULL 20
3000 30
3000
NULL 6 20
temp
2000
Insert node at the End 1
1000
struct node *temp;
temp=head;
var=(struct node *)malloc(sizeof (struct node));
var->data=value;
if(head==NULL) {
head=var;
head->next=NULL; }
else
while(temp->next!=NULL)
temp=temp->next;
var->next=NULL;
temp->next=var; 30
var
3000 2
temp 3 10
1000
NULL 30
var
3000 4
NULL 4
temp 5 10
1000
3000

5. 1 2 3 5 6 Insert node at the Middle 4 head 20 2000 1000 10 1000 3000
NULL
Insert node at the Middle
var 1
struct node *var2,*temp;
var=(struct node *)malloc(sizeof (struct node));
var->data=value;
temp=head;
if(head==NULL) {
head=var;
head->next=NULL; }
else
while(temp->data!=loc)
temp=temp->next;
var2=temp->next; (3000)
temp->next=var;
var->next=var2; 40
4000
temp 2 20
2000
1000 10
temp 3 10
1000
3000
temp 4
var 10
1000
4000 5 40
4000
3000 6

6. Delete node from end head 20 2000 1000 10 1000 4000 40 4000 3000 30
NULL
Delete node from end
struct node *temp;
temp=head;
while(temp->next != NULL) {
var=temp; //2000, 1000,4000(FINAL VALUE)
temp=temp->next;//finally 3000 }
if(temp ==head)
head=temp->next;
free(temp);
return 0;
printf("data deleted from list is %d",temp->data);
var->next=NULL;
free(temp); // free(3000) 40
4000
NULL

7. Delete node from Middle
head 20
2000
1000 10
1000
4000 40
4000
NULL
Delete node from Middle
struct node *temp,*var;
temp=head;
while(temp!=NULL) {
if(temp->data == value)
if(temp==head)
head=temp->next;
free(temp);
return 0; }
else
var->next=temp->next;
else {
var=temp;
temp=temp->next; }
}// END OF WHILE
printf("data deleted from list is %d",value);

8. Display the content of the linked list
head 20
2000
1000 10
1000
4000 40
4000
NULL
Display the content of the linked list
trav=head;
if(trav==NULL) {
printf("\nList is Empty"); }
else
printf("\nElements in the List: ");
while(trav!=NULL)
printf(" -> %d ",trav->data);
trav=trav->next;
printf("\n");

9. Doubly Linked List
Each node of the list contain two Links – one to the previous node and other to the next node.
The previous link of the first node and the next link of the last node points to NULL.
 We don’t need to keep track of the previous node for traversal or no need of traversing the whole list for finding the previous node.
More pointers needs to be handled and more links need to updated.

10. Implementation of Doubly Linked List in C
prev n
next
node
struct node {
struct node *prev;
int n;
struct node *next;
} *h, *temp, *temp1
h = NULL
To create an empty node
node
NULL n
NULL

11. Insert at beginning temp temp 10 20 1000 2000 h temp h temp1 10 20 10
if (h == NULL) {
int data;
  temp =(struct node *)malloc(1*sizeof(struct node));
temp->prev = NULL;
temp->next = NULL;
printf("\n Enter value to node : ");
scanf("%d", &data); (10)
temp->n = data;
h = temp;
temp1 = h; }
else {
int data;
  temp =(struct node *)malloc(1*sizeof(struct node));
temp->prev = NULL;
temp->next = NULL;
printf("\n Enter value to node : ");
scanf("%d", &data);
temp->n = data;
temp->next = h;
h->prev = temp;
h = temp; }
temp
temp
NULL 10
NULL
NULL 20
NULL
1000
2000 h
temp h
temp1
NULL 10
NULL
NULL 20
1000
2000 10
NULL
NULL 10
NULL
1000
2000
1000
1000

12. Insert at the end h h = temp; 20 10 2000 1000 temp temp1 temp1 temp 30
NULL 20
1000
2000 10
NULL
Insert at the end
2000
1000
if (h == NULL) {
int data;
temp =(struct node *)malloc(1*sizeof(struct node));
temp->prev = NULL;
temp->next = NULL;
printf("\n Enter value to node : ");
scanf("%d", &data);
temp->n = data;
h = temp;
temp1 = h; }
else {
int data;
temp =(struct node *)malloc(1*sizeof(struct node));
temp->prev = NULL;
temp->next = NULL;
printf("\n Enter value to node : ");
scanf("%d", &data);
temp->n = data;
temp1->next = temp;
temp->prev = temp1;
temp1 = temp; }
temp
temp1
temp1
temp
NULL 30
NULL
2000 10
NULL
2000 10
3000
1000 30
NULL
3000
1000
1000
3000
temp1 = h; (first node [10])

13. After inserting the node at the end
2000 10
3000
1000 30
NULL 20

14. Deleting the node in the Doubly Linked List
int i = 1, pos;
printf("\n Enter position to be deleted : ");
scanf("%d", &pos);
temp2 = h;
if (h == NULL) {
printf("\n Error : Empty list no elements to delete");
return; }
else
while (i < pos)
temp2 = temp2->next;
i++;
if (i == 1)
if (temp2->next == NULL)
printf("Node deleted from list");
free(temp2);
temp2 = h = NULL;
if (temp2->next == NULL) {
temp2->prev->next = NULL;
free(temp2);
printf("Node deleted from list");
return; }
temp2->next->prev = temp2->prev;
if (i != 1)
temp2->prev->next = temp2->next;
if (i == 1)
h = temp2->next;
printf("\n Node deleted");
2000 10
3000
1000 30
NULL 20

15. Display from beginning To search an item
temp2 = h;
if (temp2 == NULL) {
printf("List empty to display \n");
return; }
printf("\n Linked list elements from begining : ");
while (temp2->next != NULL)
printf(" %d ", temp2->n);
temp2 = temp2->next;
int data, count = 0;
temp2 = h;
if (temp2 == NULL) {
printf("\n Error : List empty to search for data");
return; }
printf("\n Enter value to search : ");
scanf("%d", &data);
while (temp2 != NULL)
if (temp2->n == data)
printf("\n Data found in %d position",count + 1);
else
temp2 = temp2->next;
count++;
printf("\n Error : %d not found in list", data);

16. Circularly Linked List
More complicated linked data structure.
Elements can be placed anywhere
The last node points back to the first node

17. Insert at the Beginning x y
struct node {
int data;
struct node *link; };
struct node *head = NULL, *x, *y, *z;
Creating node
head
x = (struct node*)malloc(sizeof(struct node));
printf("\n Enter the data:");
scanf("%d", &x->data); //10
x->link = x;
head = x; 10
1000
1000
Insert at the Beginning x y
x = head;
y = (struct node*)malloc(sizeof(struct node));
printf("\n Enter the data:");
scanf("%d", &y->data);
while (x->link != head) {
x = x->link; }
x->link = y;
y->link = head;
head = y; 10
1000 20
1000
2000 x y 10
2000 20
1000
1000
2000

18. Delete node at the startx
head = y;
head 10
2000 20
1000
2000
1000
Delete node at the start
if (head == NULL)
printf("\n List is empty");
else {
x = head;
y = head;
while (x->link != head)
x = x->link; }
head = y->link;
x->link = head;
free(y);
X=2000
Y=2000
While(1000 !=2000) {
X=1000; }
Ist iteration
While(2000 !=2000) { }
2nd iteration x
head=1000
x->link = 1000
free(2000) 10
1000
1000

19. head Display node details 10 2000 20 1000 2000 1000 if (head == NULL)
printf("\n List is empty");
else {
x = head;
while (x->link != head)
printf("%d->", x->data);
x = x->link; }
printf("%d", x->data);