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


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

void printList(struct Node *p);
struct Node *addFirst(struct Node *h, int x);
struct Node *removeLast(struct Node *h);


int main()
{
   struct Node *head = NULL;
   int k;

   // Insert 
   for (k = 1; k < 10; k++ )
   {
      head = addFirst(head, k);
//    printList(head);
   }      

   // Delete
   printList(head);

   for (k = 1; k < 10; k++ )
   {
      head = removeLast(head);
      printList(head);
   }      

}


// Remove the last node from the list at h
struct Node *removeLast(struct Node *h)
{
   if ( h == NULL )
      return NULL;	// Return NULL

   if ( h->next == NULL )
   {
      free(h);		// De-allocated deleted node
      return NULL;	// Return NULL
   }

   struct Node *current = h;
   struct Node *previous = h;

   while( current->next != NULL )	// Find the last node
   {
       previous = current;
       current = current->next;		// Advance to next node
   }

   previous->next = NULL; 	// Unlink the last node (from its predecessor)
   free(current);		// De-allocate deleted node

   return h;			// Return (confirm first node was unchanged)
}


// Inserts a new node containg x
// at the beginning of the list at h

struct Node *addFirst(struct Node *h, int x)
{
   struct Node *newNode = malloc( sizeof(struct Node) );

   newNode->item = x;  // Store x
   newNode->next = h;  // Make it point to h

   return newNode;
}



void printList(struct Node *p)
{
   while ( p != NULL )
   {
      printf("%d -> ", p->item);
      p = p->next;
   }
   printf("[NULL]\n");
}