public List <int> Cell_Neighboor(GrilleSudoku s, int cases)
        {
            bool       test;
            List <int> ma_list = new List <int>();

            for (int i = 0; i < s.GetVoisins().Count; i++)
            {
                test = false;

                if (s.GetVoisins()[i].Contains(cases))
                {
                    foreach (int voisin in s.GetVoisins()[i])
                    {
                        if (!ma_list.Contains(voisin) && voisin != cases)
                        {
                            ma_list.Add(voisin);
                        }
                    }
                }
            }
            return(ma_list);
        }