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



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

// push element
struct Node* insertAtFront(struct Node *listStart, int key)
{
	struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));

	newNode->nextNode = listStart;
	listStart = newNode;

	newNode->key = key;

	return listStart;
}

// pop element
int popFromFront(struct Node **pListStart)
{
	struct Node* newListStart; 
	int returnKey;

	newListStart = (*pListStart)->nextNode;
	returnKey = (*pListStart)->key;

	free(*pListStart);
	*pListStart = newListStart;
	
	return returnKey;
}

// delete first occurance of a node with a matching key.
//
// obs, denna kommer inte fungera om elementet ligger först i elementet.
// denna funktion tar bort första noden med en matchande nyckel
void deleteNodeWithKeyMatch(struct Node *listStart, int key)
{
	struct Node *currentNode, *lastNode;

	currentNode = listStart->nextNode;
	lastNode = listStart;

	while( currentNode = currentNode->nextNode )
	{
		if(currentNode->key == key)
		{
			lastNode->nextNode = currentNode->nextNode;
			free(currentNode);
			break;
		}
		lastNode = currentNode;
	}
	
	return;
}


int main(int argc, char* argv[])
{
	char a;
	struct Node* currentNode;

	// allocate memory for a node on the heap
	struct Node* listStart = (struct Node*)malloc(sizeof(struct Node));

	// Add a first item
	listStart->nextNode = NULL;
	listStart->key = 23;

	// add some more nodes
	listStart = insertAtFront(listStart, 89 );

	a=10;
	while(a-- > 0) 
		listStart = insertAtFront(listStart, a);

	// poppa 5 noder och skriv ut dem
	a = 5;
	while(listStart != NULL && a-- > 0)
	{
		printf(" %d", popFromFront(&listStart));
	}

	// Skriv ut de resterande noderna två rader nedanför
	currentNode = listStart;

	printf("\n\n");
	while(currentNode != NULL)
	{
		printf(" %d", currentNode->key);
		currentNode = currentNode->nextNode;
	}

	// waiting for a keystroke before terminating
	a = getchar();
	return 0;
}