public static boolean verifica(Albero a, Albero b) {

    if (ricercaBinaria(b, a.val()) == true) {  // PASSO BASE
        return true;
    }

    else {
        boolean latoSinistro = false;
        boolean latoDestro = false;

        if (a.sinistro != null) {
            latoSinistro = verifica(a.sinistro,b);
        }

        if (a.destro != null) {
            latoDestro = verifica(a.destro,b);
        }

        return latoSinistro || latoDestro;
    }
}

public static boolean ricercaBinaria(Albero b, int val) {

    if (b.val() == val) {  // PASSO BASE
        return true;
    }

    else if (b.val > val && b.sinistro() != null) {
        return ricercaBinaria(b.sinistro, val);
    }

    else if (b.val < val && b.destro() != null) {
        return ricercaBinaria(b.destro, val);
    }

    return false;
}