%zadanie 1
length([], Acc, Acc).

length([_|X], Acc, Length) :-
  var(Length),
  NewAcc is Acc + 1, !,
  length(X, NewAcc, Length).

length([_|X], Acc, Length) :-
  Acc =< Length,
  NewAcc is Acc + 1,

  length(X, NewAcc, Length).

/*
  length([], Acc, Acc, 0).
  length([_|X], Acc, Length, Rev):-
    NewRev is Rev-1,
    NewAcc is Acc+1,
    length(X, NewAcc, Length, NewRev).
  */
/*
connection(gliwice, wroclaw).
connection(wroclaw, warszawa).
connection(wroclaw, katowice).
connection(katowice, warszawa).
*/
connection(warszawa, krakow).
connection(krakow, warszawa).
connection(krakow, gliwice).
connection(gliwice, krakow).
connection(gliwice, warszawa).
connection(warszawa, gliwice).



/*
trip(X, X, Acc, Acc).
trip(Start, Stop, Trasa, Acc) :-
  relacja(Przystanek, Stop),
  \+ member(Przystanek, Acc),
  trip(Poczatek, Przystanek, Trasa, [Przystanek|Acc]).
*/

trip(Start, Start,ListaAkum, ListaAkum).

trip(Start, Stop, TrasaLista, ListaAkum) :-
  connection(Przystanek, Stop),
  \+ member(Przystanek, ListaAkum),
  trip(Start, Przystanek, TrasaLista, [Przystanek|ListaAkum]).

trip(Start, Stop, TrasaLista) :-
  trip(Start, Stop, TrasaLista, [Stop]).



%zadanie 4
mirror(leaf, leaf).
mirror(node(Left, Val, Right), MirrorTree) :-
  mirror(Left, MirrorLeft),
  mirror(Right, MirrorRight),
  MirrorTree = node(MirrorRight, Val, MirrorLeft).

flattn(leaf, []).
flattn(node(L, V, R), Infixed) :-
  flattn(R, PrevInfixed),
  SecondInfixed = [V|PrevInfixed],
  flattn(L, AnotherPrevInfixed),
  append(AnotherPrevInfixed, SecondInfixed, Infixed).

%zadanie 5
insert(leaf, Elem, node(leaf, Elem, leaf)).

insert(node(L, V, R), Elem, InsertedTree) :-
  Elem>=V,
  insert(R, Elem, InsertedSubTree),
  InsertedTree = node(L, V, InsertedSubTree),!.

insert(node(L, V, R), Elem, InsertedTree) :-
  insert(L, Elem, InsertedSubTree),
  InsertedTree = node(InsertedSubTree, V, R).

insertList(Tree, [], Tree).
insertList(Tree, [H|Tail], InsertedTree) :-
  insert(Tree, H, PInsertedList),
  insertList(PInsertedList, Tail, InsertedTree).
treeSort(Tree, List, SortedList) :-
  insertList(Tree, List, NewTree),
  flattn(NewTree, SortedList).


  %zadanie 7


  reverse(X,Y) :-
    reverse(X,[],Y).

  reverse([],A,A).

  reverse([H|T],A,Y) :-
    atomic(H),
    reverse(T,[H|A],Y), !.

  reverse([H|T], A, Y) :-
    reverse(H, [], NY),
    reverse(T, [NY|A], Y).