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The index page for all Programs on the site?

The DFF Play CD?

Zipped file DFF Play CD.zip contains  executable version of about  75 of the 200+ programs from the site, mostly those I particularly liked or thought would be of widest interest for non-programmers.  The file is rather large, about 20mb..

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Not a programmer (yet)?

 That's OK -  the executable version for any puzzle or  game you find here is available for download.  Just scroll down to the bottom of most any description page and you'll find a "Download executable" link. Downloaded programs are in "zipped" format to reduce size and may require an "unzipper" program unless you are running Win XP or later.  Here's a link to a free one. 

Check  out  the Most Popular  Downloads from DFF   (updated weekly)

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Notes for Teachers

 

WHAT'S NEW

March 18, 2010:  I use our "Monitor Off" program each evening to blank the monitor on my old laptop dedicated to capturing and reporting outputs from our weather station.  Monitor Off Version 2 fixes a problem a user had with the alternative code for blanking the monitor, The "Power-Off" option, should now work when the "Standby" option does not.  I have tested it under Windows 7 on my  Dell Studio 17, my  first laptop to require its use.   The program uses the Pause key to blank the monitor, regardless of the active window.

In the process of testing, I also found that the Studio 17 uses the Fn + F12 keys to emulate the missing Pause key.  I have no experience with other company's laptops, but I suspect that they all use a similar technique to replace  the seldom used Pause key with a virtual alternative.  Dell doesn't seem to document the "feature", but my Key Codes program will help find the hidden key in short order.   

 

March 11, 2010: A small bug was reported and fixed in the Computational Geometry test program, Geometry4 today. The "Draw line from point perpendicular to line" demo page (PerpSheet) did not allow the initial line to be  drawn due to a rookie coding error.  In the "mouse move"  procedure, the statement:  if (activepage=PerpSheet) or (activepage=AngleSheet) and (dragval=1) then begin needed an extra set of parentheses (colored red here) to look like this: if ((activepage=PerpSheet) or (activepage=AngleSheet)) and (dragval=1) then begin. This is the coding equivalent of writing  the algebra expression A + B * C when you meant (A + B) * C.  Results in both cases were wrong!

March 4, 2010:  A Text Spinner program suggested by a viewer was added to our Delphi Techniques section. today.  A "text spinner" randomly changes the content of a text based on some criteria, in this case a supplied set of alternative phrases embedded within the input text.  Not very practical, but an interesting intermediate level programming exercise anyway.    

February 23, 2010: I recently needed to send the log file from a newsletter mailing to help diagnose a minor problem.  However the log file contained the email addresses of each recipient and sending them in unsecured plain text did not seem like a good idea.  This  program, Obfuscate Text,  added to our Utility section, confuses email address one of two ways; replacing the name portion with a random word or replacing the entire email address with an "address removed" phrase.  In both cases, email addresses are identified by the embedded @ symbol.  As an exercise that might be useful some day, I added an option to obfuscate the word following a given word.  For example, changing the word following the word "Password:".

February 17, 2010:

Waterjugs Version 3 now solves problems with up to 7 jugs (or jars). This required a major rewrite of the previous version where run time exploded for problems larger than 4 jars.  The problems require pouring water from one jug to another to obtain a target configuration of water amounts in each jug.  At the start of the problem, we are given the capacity and the amount of liquid in each jug.  There are no graduation marks, so each pouring from jug A to jug B transfers the smaller of the liquid in A or the unused capacity of B.    The included 7 jug problem was submitted by Melanie whose program ran for days without finding a solution.  My first attempt with the old version would bomb (stack overflow error), my second attempt found the answer in 25 minutes and this version accomplishes the goal in 2 1/2 minutes.    You are welcome to pour 'til your heart's content on the 7 jug problem included, but be forewarned, the shortest solution requires 48 moves!    
 

February 10. 2010: 

Our Wind Triangle program provides mathematical and visual views of a problem every pilot, or at least every amateur pilot must wrestle with; how to get where you want to go when the wind wants to take you off course.   The answer is to head the airplane into the wind just enough to offset the distance that the wind moves you.  Version 2 lets users change colors from my default choices in order to address a problem recently reported by a pilot who happens to be color blind.   
 
 

February 4, 2010:

W O R D
O B O E
R O B E
D E E D

Word squares are square letter arrays with rows containing words which match words formed by the corresponding columns. Here is a Word Square Search program which searches a 62,000 word dictionary to create word squares based on an initial word provided by the user.   At left is one of 149 solutions found for the word "WORD".
.  

February 1, 2010:   A couple of times each year I get a request for help from a student requesting help in some project using my Reaction Times programs.  This year it was a graduate student in at a Medical School in Ecuador whose thesis topic is to test the effect of sleep deprivation on interns as result of the long hours they put in.  Her problem turned out to be decimal separator confusion because the PC she was using happened to have the Window's Locale set for a European country.  Changing back to Ecuador set it from comma back to dot and allowed her to analyze her data.  While investigating, I discovered and fixed a problem with the ResponseStats statistical analysis  program that kept a newly loaded response statistics file from being made available.  Reaction Times programs including ResponseStats Version 3.1 was uploaded today to fix the problem.

January 17, 2010:  Consider the sequence formed if, starting with any positive integer, we form a sequence where for the sequence ending with N, then next entry is N/2  if N is even and 3N+1 if N is odd.  Starting with 3 for example, the sequence is [3, 10, 5, 16, 8, 4, 2, 1].  The unproven conjecture (the "Collatz" conjecture) is that any such sequence will eventually degenerate to 1.  Here's a beginner's level program, ThreeNPlus1, that evaluates all sequences within a given range and reports the longest sequence found.  

January 12, 2010:   DFF Newsletter #55 was sent yesterday using the latest version of MailList King, a mailing list management program from Xequte Software. The program is written in Delphi and contains all the features needed to simplify newsletter sending such as automatic subscribing/unsubscribing, limiting the sending rate to comply with host server limits, processing undeliverable email responses to clean the list, etc.  The $99 personal edition does everything I need and is recommended if you ever have the need.

A university student recently took on a Java version of the MasterMind game as a school project.  He wrote asking about my "Smarter than you" intelligence level which can be applied when the program is doing the guessing about the secret pattern.  The program has a Verbose mode which was supposed to help debugging and explaining the search steps, but the messages were being cleared after each computer guess.  MasterMind Version 2.1 corrects this and hopefully will help him and others understand the mini-max guessing procedure used at the smartest level.  
   

January 9, 2010:

"Instant Insanity" is a variation of an older cube arrangement puzzle and one of a large family of similar puzzles. In this one, we have four cubes with one of four colors on each face of each cube.  The objective is to stack the cubes so each column of  faces has all four colors.

A viewer recently asked for help in developing a Delphi solver version.  Most of the online literature describes a graph search algorithm which can be applied to find solutions with pencil and paper.  With a faster but dumber computer, it's easiest just to check all 41,472 possible arrangements  looking for  solutions.  Instant Insanity Version 1.0 posted today does just that with a few sample or user defined cube sets. 


January 4, 2010:

 Red wins! 

While playing the "Wii Play" version of the Four-In-A-Row game with a grandson over the holidays, I used my Delphi version of the game to advise me on  moves to make.  I was embarrassed to find that the program's random moves "enhancement" frequently allowed Chris to win by placing 4 adjacent token in his first 4 moves - the initial random moves feature assumed that there would be no winner that soon.  Four In A Row Version 2.2 posted today fixes the problem by limiting initial random moves to 2 or 3 turns. 
   

January 2, 2010:  

Happy New Year!   We'll kick off the new year with a program that I wrote a year or so ago but never got around to posting.  Accordion Solitaire is a simple solitaire card game that is difficult to win; perhaps one win in 100 games.   This version allows user and program play and implements a "sweeper" strategy of play which can increase the odds of winning to perhaps 10%


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