LinkedList

struct Node;
typedef struct Node *PtrToNode;
typedef PtrToNode List;
typedef PtrToNode Position;

List MakeEmpty(List L);
int IsEmpty(List L);
int IsLast(Position P,List L);
Position Find(ELEMENT_TYPE X,List L);
void Delete(ELEMENT_TYPE X,List L);
Position FindPrevious(ELEMENT_TYPE X,List L);
void Insert(ELEMENT_TYPE X,List L,Position P);
void DeleteList(List L);
Position Header(List L);
Position First(List L);
Position Advance(Position P);
ELEMENT_TYPE Retrieve(Position P);


struct Node
{
	ELEMENT_TYPE Element;
	Position Next;
};


int IsEmpty( List L )
{
   return L->Next==NULL;
}

int IsLast( Position P,List L )
{
  return P->Next==NULL;
}

Position Find( ELEMENT_TYPE X,List L )
{ 
   Position P;
   P=L->Next;
   while(P!=NULL&&P->Element!=X)
	   P=P->Next;
   return P;
}

void Delete( ELEMENT_TYPE X,List L )
{
  Position p,TmpCell;
  p=FindPrevious(X,L);
  if (!IsLast(p,L))
  {
	  TmpCell=p->Next;
	  p->Next=TmpCell->Next;
	  free(TmpCell);
  }
}

Position FindPrevious( ELEMENT_TYPE X,List L )
{
   Position P;
   P=L;
   while(P->Next!=NULL&&P->Next->Element!=X)
	   P=P->Next;
   return P;
}

void Insert( ELEMENT_TYPE X,List L,Position P )
{
  Position TmpCell;
  TmpCell=malloc(sizeof(struct Node));
  if(TmpCell==NULL)
	  Error("Out of space");

  TmpCell->Element=X;
  TmpCell->Next=P->Next;
  P->Next=TmpCell;
}

void DeleteList( List L )
{
   Position P,Temp;
   P=L->Next;
   L->Next=NULL;
   while (P!=NULL)
   {
	   Temp=P->Next;
	   free(P);
	   P=Temp;
   }
}