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

struct List  // I want to use 1 prgram file for this example
{
   int value;
   struct List *next;
};


struct List *insert( struct List *head, struct List *e );
void print(struct List *h);
struct List *delete (struct List *h);


int main(int argc, char *argv[])
{
   struct List*   head = NULL;    // Empty list
   struct List *p;

   /* -------------------------------------------------
      Create a list element and insert in List at head
      ------------------------------------------------- */
   while(1)
   {
   for( int i=1; i <= 10; i++ )
   {
      p = malloc( sizeof( struct List ) );
      p->value = i;
      head = insert(head, p);       // Insert p in head
      print(head);
   } 

      for ( int i = 0; i < 10; i++ )
      {
         head = delete(head);       // Delete first element
         print(head);
      }
   }
}

/* =========================================
   insert(h, e): insert e at tail of list h
                 return new list

   A List variable is a reference variable !!!
   ========================================= */
struct List *insert( struct List* head, struct List *e )
{
   /* --------------------------------------------
       Base case: insert at the tail of an empty
      -------------------------------------------- */
   if ( head == NULL )
   {
      e->next = NULL;     // Mark e as the last list elem
      return(e);         // e is the first list elem !
   }
   else
   {
      /* ===========================================================
         Solve the problem USING the solution of a smaller problem
         =========================================================== */
      head->next = insert( head->next, e ); // Link directly to helpSol

      return head;             // Return MY solution
   }
} 




   /* ====================================================
      delete(h): delete the first elem from the list h
                 return new list
      ==================================================== */
   struct List *delete (struct List *h)
   {
      if ( h != NULL )
      {
	 struct List *help = h->next;
         free(h);
         return (help); // Return new list that starts at h.next
      }
      else 
         // deleting from empty list returns an empty list
         return NULL;
   }

// Print the list
void print(struct List *h)
{
   while (h != NULL)
   {
      printf("%d ", h->value);
      h = h->next;
   }
   printf("\n");
}