let warunek_konieczny n kubelki =
  let nwd a b =
    if y = 0 || x = 0 then x + y
    else nwd (min a b) ((max a b) mod (min a b))
  in
  let wspolny_dzielnik = ref 0 in
  for i = 0 to (n - 1) do
    wspolny_dzielnik := nwd !wspolny_dzielny (fst kubelki.(i))
  done;
  let wynik = ref true in
  for i = 0 to (n - 1) do
    if (snd kubelki.(i)) mod wspolny_dzielnik <> 0 then wynik := false;
  done;
  !wynik

let przelewanka kubelki =
  let wynik = ref -1 in
  let n = Array.size kubelki in
  if warunek_konieczny n kubelki = true then
  begin
    let koniec = Array.init n (fun i -> snd kubelki.(i)) in
    let stan_poczatkowy = Array.make n 0 in
    let q = Queue.create in
    Queue.add stan_poczatkowy q;
    let liczba_krokow = ref 0 in
    let znaleziono_wynik = ref false in
    let visited = Hashtbl.create in
    Hashtbl.add visited stan_poczatkowy 0;
    while Queue.length <> 0 && !znaleziono_wynik = false do
      let x = Queue.take q in
      let cur_odl = Hashtbl.find visited x in
      if x = koniec then
      begin
        znaleziono_wynik := true;
        wynik := cur_odl;
      end;
      (* Wylewanie *)
      for i = 0 to (n - 1) do
        let stan = Array.copy x in
        stan.(i) <- 0;
        if not (Hashtbl.mem visited stan) then
        begin
          visited := Hashtbl.add visited stan;
          Queue.add stan q;
        end
      done;
      (* Wlewanie *)
      for i = 0 to (n - 1) do
        let stan = Array.copy x in
        stan.(i) <- (fst kubelki.(i));
        if not (Hashtbl.mem visited stan) then
        begin
          visited := Hashtbl.add visited stan;
          Queue.add stan q;
        end
      done;
      (* Przelewanie *)
      for i = 0 to (n - 1) do
        for j = 0 to (n - 1) do
          if i <> j then
          begin
            let stan = Array.copy x in
            let zmiana = min stan.(i) ((fst kubelki.(j)) - x.(j)) in
            stan.(i) <- stan.(i) - zmiana;
            stan.(j) <- stan.(j) + zmiana;
            if not (Hashtbl.mem visited stan) then
            begin
              visited := Hashtbl.add visited stan;
              Queue.add stan q;
            end
          end;
        done
      done
    done
  end;
  !wynik