108 lines
2.5 KiB
C
108 lines
2.5 KiB
C
|
/*
|
||
|
|
* C Program to Reverse a Stack without using Recursion
|
||
|
|
*/
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
|
||
|
|
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;
|
||
|
|
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);
|
||
|
|
}
|
||
|
|
}
|