Delphi For Fun Newsletter #7




Monday, Nov 6, 2000

I'm cheating this week and just copying the What's New section of the home page.    Hunting season has opened, so play time will be divided for the next few weeks.  I had a wonderful first week, without firing a shot.  Heard the crows exercise their lungs every morning, had a grouse wake up in a pine tree about 6 feet from my head,   saw turkeys when I had my squirrel gun and squirrels when I had my turkey gun.  Saw a big old doe chase two young ones from under the apple tree so she could  return and browse at leisure after dark  (deer, like pilots, are old or bold -  rarely both).  All in all, an entirely satisfying first week.    One more week of turkey season before deer season opens.  Time to get serious. 

November 6:  AirportSim, an airport simulation program is available.  It's a first step toward future explorations of discrete event simulation (airports, banks, gas stations, grocery stores, factories -  anywhere people or things show up for some service, get it,  and leave).    We can even count the number of  planes that run out of fuel while waiting to land. (No lives were lost in the creation of this program.)

 November 3: "Insert + and - signs as necessary into the string 123456789 to form an expression that evaluates to 100".    I received this problem yesterday in an e-mail from an 11 year old boy who says his teacher assigned it.  I told him that it would probably take me 2 hours to write the program, so if he would spend 2 hours working on it and send me his closest solution, I'd send him the program. I haven't heard back, but I couldn't resist coding it anyway.    How would you solve it?  Here's my solution, called  Expressions 100.

November 2:  Uli from Switzerland, just let me know that the Knight's Tour does not compile under Delphi 3.  Thanks Uli.  Apparently D3 doesn't support dynamic arrays (arrays that can change size at run time).   I've made a version that doesn't use dynamic arrays.  If anyone else has the same problem, let me know.   There may be other programs posted that use dynamic arrays or other features that didn't exist in earlier Delphi versions.   Please, let me know if you encounter problems using downloaded source code.

November 1:  Magic Squares #1 generates Magic Squares of odd size (up to 51x51).  This a simple introduction to another interesting mathematical niche.  (Magic Squares, in case you have never seen them, are square arrays of the integers from 1 to N2 arranged in an NxN matrix so that each row, column, and corner-to-corner diagonal sums to the same number. )   Another problem only made solvable because some smart mathematicians developed an algorithm a few hundred years ago.     

Hey, we're up over 1400 cumulative visitors this week.
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Gary Darby
"Science is what we understand well enough to explain to a computer.  Art is everything else."  (Donald Knuth - pioneer in the field of Analysis of Algorithms)