Program 12 - Reverse a Linked List

	#include <stdio.h>
	struct node{
	int data;
	struct node *next;
	};
	struct node *start = NULL, *last = NULL;
	void create(){
	int num;
	struct node *nn;
	printf("Enter data: ");
	scanf("%d", &num);
	while(num != -1){
	nn = (struct node *)malloc(sizeof(struct node));
	nn -> data = num;
	nn -> next = NULL;
	if(start == NULL){
	start = nn;
	last = nn;
	} else {
	last -> next = nn;
	last = nn;
	}
	printf("Enter data or enter -1 to stop: ");
	scanf("%d", &num);
	}
	}
	void reverse(){
	struct node *prev = NULL, *curr = NULL;
	if(start == NULL){
	printf("Empty Linked list\n");
	} else if(start -> next == NULL){
	printf("Reversing Linked List....\n");
	printf("The list has been reversed\n");
	return;
	} else {
	printf("Reversing Linked List....\n");
	/*
	|start| -> |prev| -> |curr| ->......
	Which logic seems ezier? This one or the one in Sorting Algorithmns
	*/
	prev = start -> next;
	curr = prev -> next;
	start -> next = NULL;
	prev -> next = start;
	start = prev;
	while(curr != NULL){
	prev = curr;
	curr = curr -> next;
	prev -> next = start;
	start = prev;
	}
	printf("The list has been reversed\n");
	}
	}
	void display(){
	struct node *p;
	if(start == NULL){
	printf("Empty Linked list\n");
	} else {
	p = start;
	while(p != NULL){
	printf("%d ->", p -> data);
	p = p -> next;
	}
	printf("NULL\n");
	}
	}
	int main(){
	printf("***Create Linked List***\n");
	create();
	system("cls");
	printf("The list is: \n");
	display();
	reverse();
	printf("The new list is: \n");
	display();
	}