linked-list-reverse.c

#include <stdio.h>
#include <stdlib.h>

typedef struct node {
	int element;
	struct node * prev;
	struct node * next;
} node;

node * HEAD, * TAIL;

int main() {

	HEAD = NULL;
	TAIL = NULL;

	int n;
	printf("Enter the number of elements: ");
	scanf("%d", &n);

	int i, temp;
	node * thisNode;
	for(i = 0; i < n; ++i) {
		printf("Enter a LL element: ");
		scanf("%d", &temp);

		thisNode = ((node *) malloc(sizeof(node)));
		thisNode->element = temp;
		thisNode->next = NULL;
		thisNode->prev = NULL;

		if (!HEAD) {
			HEAD = thisNode;
		}

		if (TAIL) {
			thisNode->prev = TAIL;
			TAIL->next = thisNode;
		}

		TAIL = thisNode;
	}

	printf("\nLinked list in order: ");
	thisNode = HEAD;
	while(thisNode) {
		printf("%d ->", thisNode->element);
		thisNode = thisNode->next;
	}
	printf("\nLinked list in reverse order: ");
	thisNode = TAIL;
	while(thisNode) {
		printf(" %d ->", thisNode->element);
		thisNode = thisNode->prev;
	}

	return 0;
}