Daily Archives: November 26, 2010

The Friday Fragment

It’s Friday, and time again for the Friday Fragment: our weekly programming-related puzzle.

This Week’s Fragment

Having finished a series of game bots, we’ll have a Thanksgiving change of pace and do another cryptogram.  Crack the following cipher:


You can provide the solution or just offer suggestions on how to go about solving it.  For example, I can’t solve it, but based on its background (try some googling), I have ideas about how it might be solved.  To “play along,” post your response as a comment or send it via email.

Last Week’s Fragment – Solution

Last week’s puzzle was to code a simple Reversi competition:

Write code to call competing Reversi bots, flip pieces, and score the results.

Here’s a solution in PHP.  

  $urls[0] = 'http://derekwilliams.us/bots/reversi';
  $urls[1] = $urls[0];  // Your bot here
  $pieces = array('X', 'O');
  $board = str_repeat('.',64);
  $board[27]='O'; $board[28]='X';
  $board[35]='X'; $board[36]='O';
  $player = 0;

  for ($i=0; $i<64; $i++) {;
    $play = file_get_contents($urls[$player].'?board='.$board.'&piece='.$pieces[$player]);
    $board = update_board($board, $play);
    $player = $player == 0 ? 1 : 0;

  function show_board($board) {
    $scores = array('.' => 0, 'X' => 0, 'O' => 0);
    echo '<table border="1">';
    for ($i=0; $i<8; $i++) {
      echo '<tr border="1">';
      for ($j=0; $j<8; $j++) {
        $piece = $board[($i*8)+$j];
        echo '<td border="1">'.$piece.'&nbsp;</td>';
      echo '</tr>';
    echo '</table><p>&nbsp;</p>';
    printf("<p>X: %d, O: %d</p>", $scores['X'], $scores['O']);
    if ($scores['.'] == 0)
      exit(printf("<p>%s wins!</p>", $scores['X'] > $scores['O'] ? 'X' : 0));

You can run this solution and other bots from the links at http://derekwilliams.us/bots.  This page also includes full source code, including helper functions.

Microsoft SOAP – Lather, Restart, Repeat

A friend recently asked me to add web service wrappers around some C# .NET code I had written awhile back.  Since Microsoft invented SOAP/XML, it’s not surprising that it’s easy to do in .NET: just create the ASMX file and WebService subclass (with WebService and WebMethod attributes), and .NET handles the rest.  Visual Studio (in my case, VS 2008) even provides templates and wizards to create these for you: nice things like New Web Site – ASP .NET Web Service and Add New Item – Web Service.

I drank the .NET Kool-Aid back when I built this system and constructed with layers of assemblies.  So re-use was fairly straightforward: just add calls to methods (DLL entry points) in the appropriate layer.  Here again, with “Add Reference” and using clauses, Visual Studio makes it very easy.  That is, except for the bugs.

I occasionally got the familiar “type or namespace could not be found” error.  I assumed I had messed up a reference or using clause, or had a problem with the referenced assembly or one of its children.  But every possible cure for these yielded no joy.  Intellisense recognized the references just fine, but the compile/build didn’t.  The solution?  Restart Visual Studio.

This is a recurring bug which seems to move to new areas with each new VS release or fix.  In this case, it seems to be unique to web services referencing .NET assemblies, but it may pop up in other areas.  If I did regular .NET development (like maybe for my day job), I’d keep current on releases and fix levels.  But for this quick exercise, I stuck to the familiar Windoze-land solution: take one restart and call me in the morning.