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Posted 14 Mar 2005


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C# vs. VB contest - Resolving Mac Mahon problem using .NET

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3.40/5 (16 votes)
14 Mar 20053 min read
Rather than discussing forever whether C# is better than VB or vice-versa, let's see which programmers are best.

Sample Image - macmahon2.png


For the last two years, every couple of months or so, an article appears claiming “C# is faster than VB.NET”. I agree C# is possibly very slightly faster, I won’t argue. Perhaps it is only fair. Perhaps it is to compensate the fact that C# programmers are probably not as good as VB programmers. You understand that it is time to revive a good old war like we had years ago between Atari and Amiga. If we can't decide which Language is the best, let's see which programmers are the best, whether it is VB programmers or C# programmers.

The Mac Mahon Problem

The problem I want to challenge you with is this one.

You have to complete a puzzle made of 24 pieces. The pieces are displayed in the picture at the beginning of this article.

  1. All the 24 pieces must be used.
  2. Each piece can be rotated to any orientation.
  3. Each segment color must match the color of the adjoining segment.
  4. The puzzle border must be of the same color (red in this case).

This problem can be reproduced on cardboard to play as a solitaire.

A Valid Solution

This is one solution of the problem.

As you can see:

  • It uses all 24 pieces.
  • The border is all red.
  • Each piece shares a color with each of its neighbours.

The Challenge

The challenge is to make a program which looks for a solution for this puzzle. The program has to count how many solutions the puzzle has, and then do it as fast as possible. The existing code is already searching, but not very fast. I let my computer run 24 hours and it did not complete…

VB.NET Results

Date Description Result

First release
by Pascal GANAYE

10,000 results in more than 24 hours. Did not complete
15/03/2005 Added a few optimizations 106624 solutions in 90 minutes

C# Results

Date Description Result

No submission yet

17/03/2005 Marc Clifton started a C# 77,306 solutions in about 60 minutes

Other Languages

I would love to see another language here. If you have a try, please post something in the forum below.

Points of Interest

As you can see, each piece is divided in 4 triangles and filled with 3 colours. Mathematically, this is a nice problem, because this it is not 24 arbitrary chosen pieces but every single combination. There are 3*3*3*3 = 81 possibilities. But if you remove the duplicates, you end up with only 24 different pieces.

Submission Rules

  • I will post one submission in each submitted language. You can also use this page forum at the bottom.
  • The program can use any sort of optimisation as long as it stays managed .NET and native language (can’t use MSIL).
  • All optimisations must be described. Please no hard coded solution.

I suggest a notation structure for the solutions. If you name the piece A0,B0,C0,...X0.

Sample screenshot A0 Sample screenshot B0 Sample screenshot C0 Sample screenshot D0 Sample screenshot E0 Sample screenshot F0
Sample screenshot G0 Sample screenshot H0 Sample screenshot I0 Sample screenshot J0 Sample screenshot K0 Sample screenshot L0
Sample screenshot M0 Sample screenshot N0 Sample screenshot O0 Sample screenshot P0 Sample screenshot Q0 Sample screenshot R0
Sample screenshot S0 Sample screenshot T0 Sample screenshot U0 Sample screenshot V0 Sample screenshot W0 Sample screenshot X0

The rotated version of Sample screenshot B0 would be called:

Sample screenshot B1 (90 degrees anti-clockwise)

Sample screenshot B2 (180 degrees), and

Sample screenshot B3 (270 degrees).

Then a solution like this one:

could be written like this:

B2 D0 I0 L0 J0 G0
A0 C2 V0 S0 T2 O3
K0 F0 X0 W0 U0 Q3
H2 E0 P2 R2 M2 N3

or even as a single line like this:


This will probably help to compare our results.

You can see mine here.

Last Notes

I hope you realize, I don't take this language war very seriously. I just love the Mac-Mahon problem. How can we live without knowing for sure how many solutions there are?


  • 14th March, 2005: Initial version


This article has no explicit license attached to it, but may contain usage terms in the article text or the download files themselves. If in doubt, please contact the author via the discussion board below. A list of licenses authors might use can be found here.


About the Author

Pascal Ganaye
Software Developer (Senior)
France France
I am a French programmer.
These days I spend most of my time with the .NET framework, JavaScript and html.

Comments and Discussions

GeneralYour link is incorrect Pin
Mustafa Ismail Mustafa22-Nov-07 12:13
MemberMustafa Ismail Mustafa22-Nov-07 12:13 
GeneralRe: Your link is incorrect Pin
Pascal Ganaye7-Jan-08 0:35
MemberPascal Ganaye7-Jan-08 0:35 
General5784 Pin
ColinDavies17-Apr-05 0:21
MemberColinDavies17-Apr-05 0:21 
GeneralRe: 5784 Pin
Pascal Ganaye20-Apr-05 14:53
MemberPascal Ganaye20-Apr-05 14:53 
GeneralI am a bit embarassed... Pin
Pascal Ganaye9-Apr-05 13:12
MemberPascal Ganaye9-Apr-05 13:12 
GeneralIf this is what I think it is... Pin
Daniel Turini7-Apr-05 0:53
MemberDaniel Turini7-Apr-05 0:53 
GeneralResults Pin
Pascal Ganaye6-Apr-05 10:08
MemberPascal Ganaye6-Apr-05 10:08 
GeneralRe: Results Pin
Giancarlo Aguilera7-Apr-05 14:06
MemberGiancarlo Aguilera7-Apr-05 14:06 
GeneralC++ solution Pin
Jon5-Apr-05 0:34
MemberJon5-Apr-05 0:34 
GeneralRe: C++ solution Pin
Bojan Rajkovic5-Apr-05 16:44
MemberBojan Rajkovic5-Apr-05 16:44 
GeneralRe: C++ solution Pin
Jon5-Apr-05 22:36
MemberJon5-Apr-05 22:36 
GeneralRe: C++ solution Pin
Pascal Ganaye6-Apr-05 10:12
MemberPascal Ganaye6-Apr-05 10:12 
GeneralRe: C++ solution Pin
Marc Clifton9-Apr-05 7:16
mvaMarc Clifton9-Apr-05 7:16 
GeneralSolved in 67 seconds Pin
Marc Clifton31-Mar-05 3:53
mvaMarc Clifton31-Mar-05 3:53 
GeneralRe: Solved in 67 seconds Pin
Pascal Ganaye31-Mar-05 9:40
MemberPascal Ganaye31-Mar-05 9:40 
GeneralRe: Solved in 67 seconds Pin
Marc Clifton31-Mar-05 10:56
mvaMarc Clifton31-Mar-05 10:56 
GeneralRe: Solved in 67 seconds Pin
Pascal Ganaye1-Apr-05 9:09
MemberPascal Ganaye1-Apr-05 9:09 
GeneralC# Algorithm Pin
Bojan Rajkovic21-Mar-05 11:05
MemberBojan Rajkovic21-Mar-05 11:05 
GeneralRe: C# Algorithm Pin
Pascal Ganaye21-Mar-05 12:53
MemberPascal Ganaye21-Mar-05 12:53 
GeneralOptimizations Pin
Pascal Ganaye19-Mar-05 3:48
MemberPascal Ganaye19-Mar-05 3:48 
General Pin
Pascal Ganaye16-Mar-05 13:08
MemberPascal Ganaye16-Mar-05 13:08 
General5.2 million and counting Pin
Marc Clifton16-Mar-05 0:36
mvaMarc Clifton16-Mar-05 0:36 
GeneralRe: 5.2 million and counting Pin
Pascal Ganaye16-Mar-05 11:21
MemberPascal Ganaye16-Mar-05 11:21 
GeneralRe: 5.2 million and counting Pin
Marc Clifton16-Mar-05 15:01
mvaMarc Clifton16-Mar-05 15:01 
GeneralThe number of results battle. Pin
Pascal Ganaye16-Mar-05 11:52
MemberPascal Ganaye16-Mar-05 11:52 

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