Code:
#include stdio.h
#include stdlib.h
struct node
{
int num;
struct node *next;
};
void create(struct node **);
void tocircular(struct node **);
void release(struct node **);
void change(struct node **, int);
void display(struct node *);
int main()
{
struct node *p = NULL;
int num;
printf("Enter data into the list\n");
create(&p);
tocircular(&p);
printf("Circular list generated\n");
display(p);
printf("Enter node position to interchange with it's adjacent: ");
scanf("%d", &num);
change(&p, num - 2);
printf("After interchanging, ");
display(p);
release (&p);
return 0;
}
void tocircular(struct node **p)
{
struct node *rear;
rear = *p;
while (rear->next != NULL)
{
rear = rear->next;
}
rear->next = *p;
/*After this the singly linked list is now circular*/
}
void change(struct node **head, int num)
{
struct node *p, *q, *r;
p = q = r = *head;
p = p->next->next;
q = q->next;
while (num != 0)
{
r = q;
q = p;
p = p->next;
num--;
}
r->next = p;
q->next = p->next;
p->next = q;
}
void create(struct node **head)
{
int c, ch;
struct node *temp, *rear;
do
{
printf("Enter number: ");
scanf("%d", &c);
temp = (struct node *)malloc(sizeof(struct node));
temp->num = c;
temp->next = NULL;
if (*head == NULL)
{
*head = temp;
}
else
{
rear->next = temp;
}
rear = temp;
printf("Do you wish to continue [1/0]: ");
scanf("%d", &ch);
} while (ch != 0);
printf("\n");
}
void display(struct node *head)
{
struct node *temp = head;
printf("Displaying the list elements\n");
printf("%d\t", temp->num);
temp = temp->next;
while (head != temp)
{
printf("%d\t", temp->num);
temp = temp->next;
}
printf("\n");
}
void release(struct node **head)
{
struct node *temp = *head;
temp = temp->next;
(*head)->next = NULL;
(*head) = temp->next;
while ((*head) != NULL)
{
free(temp);
temp = *head;
(*head) = (*head)->next;
}
}
Output:
Enter data into the list
Enter number: 1
Do you wish to continue [1/0]: 1
Enter number: 2
Do you wish to continue [1/0]: 1
Enter number: 3
Do you wish to continue [1/0]: 1
Enter number: 4
Do you wish to continue [1/0]: 1
Enter number: 5
Do you wish to continue [1/0]: 0
Circular list generated
Displaying the list elements
1 2 3 4 5
Enter node position to interchange with it's adjacent: 2
After interchanging, Displaying the list elements
1 3 2 4 5
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