public static string[] GetResults(int n, string[] grid)
        {
            if (n < 2) return grid;

            var plantedGrid = GetPlantedGrid(grid);

            var bombs = GetCurrentBombs(grid);

            var planted = false;

            for (var seconds = 2; seconds <= n; seconds++)
            {

                if (!planted)
                {
                    planted = true;
                    continue;
                }

                if (planted)
                {
                    BlowBombs(plantedGrid, bombs);
                    bombs = GetCurrentBombs(grid);
                    planted = false;
                }
            }

            return grid;
        }

        private static List<Bomb> GetCurrentBombs(string[] grid)
        {
            var result = new List<Bomb>();

            for (var lineIndex = 0; lineIndex < grid.Length; lineIndex++)
            {
                if (!grid[lineIndex].Contains('O'))
                    continue;

                for(var ind = grid[lineIndex].IndexOf('O'); ind > -1; ind = grid[lineIndex].IndexOf('O', ind + 1))
                {
                    result.Add(new Bomb { X = lineIndex, Y = ind });
                }
            }

            return result;
        }

        private static string[] GetPlantedGrid(string[] grid)
        {
            string[] result = new string[grid.Length];

            for(var i = 0; i < grid.Length; i++)
            {
                result[i] = grid[i].Replace('.', 'O');
            }

            return result;
        }

        private static void BlowBombs(string[] grid, List<Bomb> bombs)
        {
            foreach(var bomb in bombs)
            {
                grid[bomb.X] = grid[bomb.X].Remove(bomb.Y, 1).Insert(bomb.Y, ".");

                if (bomb.X != 0 && bomb.X != grid.Length - 1)
                {
                    grid[bomb.X - 1] = grid[bomb.X - 1].Remove(bomb.Y, 1).Insert(bomb.Y, ".");
                    grid[bomb.X + 1] = grid[bomb.X + 1].Remove(bomb.Y, 1).Insert(bomb.Y, ".");

                }
                else if(bomb.X == 0 && grid.Length > 1)
                {
                    grid[bomb.X + 1] = grid[bomb.X + 1].Remove(bomb.Y, 1).Insert(bomb.Y, ".");
                }
                else if(bomb.X == grid.Length - 1 && grid.Length - 1 > 0)
                {
                    grid[bomb.X - 1] = grid[bomb.X - 1].Remove(bomb.Y, 1).Insert(bomb.Y, ".");
                }

                if(bomb.Y != 0 && bomb.Y != grid[bomb.X].Length - 1)
                {
                    grid[bomb.X] = grid[bomb.X].Remove(bomb.Y - 1, 1).Insert(bomb.Y - 1, ".").Remove(bomb.Y + 1, 1).Insert(bomb.Y + 1, ".");
                }
                else if(bomb.Y == 0 && grid[bomb.X].Length > 1)
                {
                    grid[bomb.X] = grid[bomb.X].Remove(bomb.Y + 1, 1).Insert(bomb.Y + 1, ".");
                }
                else if(bomb.Y == grid[bomb.X].Length - 1 && grid[bomb.X].Length > 1)
                {
                    grid[bomb.X] = grid[bomb.X].Remove(bomb.Y - 1, 1).Insert(bomb.Y - 1, ".");
                }
            }

            bombs.Clear();
        }

        private class Bomb
        {
            public int X { get; set; }

            public int Y { get; set; }
        }