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108 lines
2.5 KiB
C
108 lines
2.5 KiB
C
/*
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* C Program to Reverse a Stack without using Recursion
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*/
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#include <stdio.h>
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#include <stdlib.h>
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struct node
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{
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int a;
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struct node *next;
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};
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void generate(struct node **);
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void display(struct node *);
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void stack_reverse(struct node **);
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void delete(struct node **);
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int main()
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{
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struct node *head = NULL;
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generate(&head);
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printf("\nThe sequence of contents in stack\n");
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display(head);
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printf("\nInversing the contents of the stack\n");
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stack_reverse(&head);
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printf("\nThe contents in stack after reversal\n");
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display(head);
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delete(&head);
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return 0;
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}
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void stack_reverse(struct node **head)
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{
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struct node *temp, *prev;
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if (*head == NULL)
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{
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printf("Stack does not exist\n");
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}
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else if ((*head)->next == NULL)
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{
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printf("Single node stack reversal brings no difference\n");
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}
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else if ((*head)->next->next == NULL)
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{
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(*head)->next->next = *head;
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*head = (*head)->next;
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(*head)->next->next = NULL;
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}
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else
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{
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prev = *head;
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temp = (*head)->next;
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*head = (*head)->next->next;
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prev->next = NULL;
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while ((*head)->next != NULL)
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{
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temp->next = prev;
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prev = temp;
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temp = *head;
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*head = (*head)->next;
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}
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temp->next = prev;
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(*head)->next = temp;
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}
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}
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void display(struct node *head)
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{
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if (head != NULL)
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{
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printf("%d ", head->a);
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display(head->next);
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}
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}
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void generate(struct node **head)
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{
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int num, i;
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struct node *temp;
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printf("Enter length of list: ");
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scanf("%d", &num);
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for (i = num; i > 0; i--)
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{
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temp = (struct node *)malloc(sizeof(struct node));
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temp->a = i;
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if (*head == NULL)
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{
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*head = temp;
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(*head)->next = NULL;
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}
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else
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{
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temp->next = *head;
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*head = temp;
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}
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}
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}
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void delete(struct node **head)
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{
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struct node *temp;
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while (*head != NULL)
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{
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temp = *head;
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*head = (*head)->next;
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free(temp);
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}
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} |