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

struct Node {
	struct Node * next;
	int key;
};

/*
 * Insert a new node first in the list. The argument head is assumed to be NULL 
 *  when the list is empty.
 */
struct Node * push_front(struct Node * head, int key){
	
	struct Node * newNode = (struct Node*)malloc(sizeof(struct Node));
	(*newNode).key = key; // newNode->key = key;
	newNode->next = head;
	
	return newNode;
}

struct Node * push_back(struct Node * head, int key){
	struct Node * current;
	struct Node * newNode = (struct Node*)malloc(sizeof(struct Node));
	newNode->key = key;
	newNode->next = NULL;
	
	// speciall fall för tom lista
	if(head == NULL){
		return newNode;
	}
	
	// ta oss till sista elementet
	current = head;
	while(current->next != NULL){
		current = current->next;
	}
	current->next = newNode;
	
	return head;
}

void printList(struct Node * head){
	
	while(head){
		printf("%i ", head->key);
		head = head->next;
	}
}

void freeList(struct Node * head){
	struct Node * nextNode;
	
	while(head){
		nextNode = head->next;
		free(head);
		head = nextNode;
	}
}

// returnera key för först elementet, ta sedan bort första elementet.
int pop_front(struct Node ** head){
	int tmp;
	
	tmp = (*head)->key;
	*head = (*head)->next;
	return tmp;
}

int main(int argc, char **argv)
{
	struct Node * listHead;
	int tmp = 9;
	listHead = NULL;
	
	freeList(listHead);
	
	listHead = push_front(listHead, 89);
	
	tmp = pop_front(&listHead);
	
	while(tmp-- > 0)
		listHead = push_front(listHead, tmp);
	
	tmp = 5;
	
	while(tmp-- > 0)
		listHead = push_back(listHead, tmp);
		
	printList(listHead);
	freeList(listHead);
	printf("hello world\n");
	return 0;
}