Reverse a Stack without using Recursion
#include
#include
#include
struct node
{
int a;
struct node *next;
};
void generate(struct node **);
void display(struct node *);
void stack_reverse(struct node **);
void delete(struct node **);
int main()
{
struct node *head = NULL;
clrscr();
generate(&head);
printf("\nThe sequence of contents in stack\n");
display(head);
printf("\nInversing the contents of the stack\n");
stack_reverse(&head);
printf("\nThe contents in stack after reversal\n");
display(head);
delete(&head);
return 0;
}
void stack_reverse(struct node **head)
{
struct node *temp, *prev;
if (*head == NULL)
{
printf("Stack does not exist\n");
}
else if ((*head)->next == NULL)
{
printf("Single node stack reversal brings no difference\n");
}
else if ((*head)->next->next == NULL)
{
(*head)->next->next = *head;
*head = (*head)->next;
(*head)->next->next = NULL;
}
else
{
prev = *head;
temp = (*head)->next;
*head = (*head)->next->next;
prev->next = NULL;
while ((*head)->next != NULL)
{
temp->next = prev;
prev = temp;
temp = *head;
*head = (*head)->next;
}
temp->next = prev;
(*head)->next = temp;
}
}
void display(struct node *head)
{
if (head != NULL)
{
printf("%d ", head->a);
display(head->next);
}
}
void generate(struct node **head)
{
int num, i;
struct node *temp;
printf("Enter length of list: ");
scanf("%d", &num);
for (i = num; i > 0; i--)
{
temp = (struct node *)malloc(sizeof(struct node));
temp->a = i;
if (*head == NULL)
{
*head = temp;
(*head)->next = NULL;
}
else
{
temp->next = *head;
*head = temp;
}
}
}
void delete(struct node **head)
{
struct node *temp;
while (*head != NULL)
{
temp = *head;
*head = (*head)->next;
free(temp);
}
}
Output
Enter length of list: 8
The sequence of contents in stack
1 2 3 4 5 6 7 8
Inversing the contents of the stack
The contents in stack after reversa
l 8 7 6 5 4 3 2 1
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