private static void HideRandomly(int count, int[,] cells)
{
var indexes = CollectionExtensions.CreateIndexesFromZeroToCount(Game.SudokuSize * Game.SudokuSize);
for (var i = 0; i < count; i++)
{
var index = CollectionExtensions.PickRandomIndex(indexes);
indexes.Remove(index);
var cell = ToCell(index);
cells[cell.Y, cell.X] = 0;
}
}
