Tournament Brackets algorithm - asp.net

Question

I need to create an asp.net page that auto generate a brackets tournament tennis style.
Regarding the managing of match in database, it's not a problem.
The problem is the dynamic graphics creation of brackets.
The user will be able to create tournament by 2-4...32 players.
And i don't know ho to create the graphics bracket in html or gdi...

Answer 1

Using Silverlight, and a Grid, You can produce something like this:
To do it, define a regular UserControl containing a Grid. (This is the default when you build a silverlight app in VS2008 with the Silverlight 3.0 SDK).
Then, add a call to the following in the constructor for the user control:
private void SetupBracket(int n)
{
var black = new SolidColorBrush(Colors.Gray);
// number of levels, or rounds, in the single-elim tourney
int levels = (int)Math.Log(n, 2) + 1;
// number of columns in the Grid. There's a "connector"
// column between round n and round n+1.
int nColumns = levels * 2 - 1;
// add the necessary columns to the grid
var cdc = LayoutRoot.ColumnDefinitions;
for (int i = 0; i < nColumns; i++)
{
var cd = new ColumnDefinition();
// the width of the connector is half that of the regular columns
int width = ((i % 2) == 1) ? 1 : 2;
cd.Width = new GridLength(width, GridUnitType.Star);
cdc.Add(cd);
}
var rdc = LayoutRoot.RowDefinitions;
// in the grid, there is one row for each player, and
// an interleaving row between each pair of players.
int totalSlots = 2 * n - 1;
for (int i = 0; i < totalSlots; i++)
{
rdc.Add(new RowDefinition());
}
// Now we have a grid of the proper geometry.
// Next: fill it.
List<int> slots = new List<int>();
ImageBrush brush = new ImageBrush();
brush.ImageSource = new BitmapImage(new Uri("Bridge.png", UriKind.Relative));
// one loop for each level, or "round" in the tourney.
for (int j = 0; j < levels; j++)
{
// Figure the number of players in the current round.
// Since we insert the rounds in the reverse order,
// think of j as the "number of rounds remaining."
// Therefore, when j==0, playersThisRound=1.
// When j == 1, playersThisRound = 2. etc.
int playersThisRound = (int)Math.Pow(2, j);
int x = levels - j;
int f = (int)Math.Pow(2, x - 1);
for (int i = 0; i < playersThisRound; i++)
{
// do this in reverse order. The innermost round is
// inserted first.
var r = new TextBox();
r.Background = black;
if (j == levels - 1)
r.Text = "player " + (i + 1).ToString();
else
r.Text = "player ??";
// for j == 0, this is the last column in the grid.
// for j == levels-1, this is the first column.
// The grid column is not the same as the current
// round, because of the columns used for the
// interleaved connectors.
int k = 2 * (x - 1);
r.SetValue(Grid.ColumnProperty, k);
int m = (i * 2 + 1) * f - 1;
r.SetValue(Grid.RowProperty, m);
LayoutRoot.Children.Add(r);
// are we not on the last round?
if (j > 0)
{
slots.Add(m);
// Have we just inserted two rows? Then we need
// a connector between these two and the next
// round (the round previously added).
if (slots.Count == 2)
{
string xamlTriangle = "<Path xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation' "+
"xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' " +
"Data='M0,0 L 100 50 0 100 Z' Fill='LightBlue' Stretch='Fill'/>";
Path path = (Path)System.Windows.Markup.XamlReader.Load(xamlTriangle);
path.SetValue(Grid.ColumnProperty, 2 * (x - 1) + 1);
path.SetValue(Grid.RowProperty, slots[0]);
path.SetValue(Grid.RowSpanProperty, slots[1] - slots[0] + 1);
this.LayoutRoot.Children.Add(path);
slots.Clear();
}
}
}
}
}
In the above, the connector is just an isosceles triangle, with the apex pointing to the right. It is generated by XamlReader.Load() on a string.
You would also want to pretty it up, style it with different colors and fonts, I guess.
You can insert this silverlight "user control" into any HTML web page, something like embedding a flash app into a page. There are silverlight plugins for IE, Firefox, Opera, Safari, and Chrome.
If you don't want to use Silverlight, you could use a similar approach to construct an HTML table.