Delphi
For Fun Newsletter #36
Spring
has sprung here in the mountains of Virginia, so programming will be on its
summertime schedule. It’s
been an exciting couple of months, including a new grandbaby, Nathan,
born on March 9th!
We’re heading out next week to see how much he’s grown in 2 months.
And
the week after, we’ll be attending the Destination
Imagination "Global"
Finals in Knoxville, TN. A
young lady wrote to me some time ago asking about pendulums – an
important element in the skit they are presenting.
She has kept me posted since then, and last month they won the South
Carolina championship in their division!
I just can’t
resist the chance to go down and see this thing in action when they compete in
Knoxville.
There
are a couple of new programs this period: ”Missionaries and Cannibals”
puzzle ,
and a word puzzle I call
“Scrambled Pie".
Plus the usual fix-ups and enhancements including a 5/6
peg version of the Mastermind game and a "Crackerbarrel"
version of Peg Solitaire.
Enjoy!
Here's
the rest of What's New since last time:
March
4, 2004: My old
business partner asked recently if I could do a version of the triangular
peg puzzle similar to those for in Cracker Barrel restaurants.
Getting down to one peg left is driving his wife crazy! I re-posted a Peg
Solitaire version today which includes it. I didn't not redo the
drawing routines to draw an equilateral triangle, but you can play a right angle
triangle version with 5, 6, or 7 holes per side. (If you can solve these, just
mentally rotate the 5-per-side puzzle by 45 degrees and Cracker Barrel will be
labeling you as a "Genius". ) Note that
"Auto-solve" has not yet solved the "one peg left"
7-per-side version so I don't even know if a solution exits. If you let
your PC run it long enough to find out, let me know.
March 6, 2004: Sharp-eyed
viewer, C. Doumar, spotted a bug in the auto-solve triangular puzzle code. It
now finds quick "1 peg remaining" solutions for the
6-pegs-per-side cases. I reposted Peg
Solitaire today with that fix. 7-pegs per-side is still not so
quick.
March 9,
2004: It's a boy! Just to let DFF viewers know that
programming will take a back seat for the next week or two. Somebody
has to hold the new grandson and, once in a while, it is even my turn!
I'll get back to e-mail responses and projects when the excitement dies down.
March13, 2004: Grandma
won't let me have the baby so I fixed a small problem in Intersecting
Lines demo over in Math Topics. Viewer Phil Hackett had pointed out
earlier this month that testing parallel lines caused a "divide by
zero" exception instead of a "Lines do not intersect" message -
now fixed. And Grandma's turn is up. Thanks Phil.
March 23, 2004:
We're home! When Amy thanked us for helping out with the new baby, I
thanked her back for providing us one more chance to experience miracle of new
life. Trying writing a program to do that!
I received an email last week from a
beginning Delphi programmer asking for help with a program in which the user
dragged colors to make guesses of a secret pattern. It
triggered a question about how simple the drag/drop part could be. The
answer is in this Simple
Drag Drop program. OK, OK, to kill the suspense - the answer is
just two lines of user written code! Surprised even me.
We may finish the rest of the puzzle this week - just for fun.
March
26, 2004: A viewer today
raised some question about the Making
Change program , which solves the number of ways to make change for $1 and
some other making change problems. (I think he thinks there are only
289 ways, but it wasn't entirely clear.) In any event I ran version 2 of
the program and couldn't even understand my description of the
"Minimum coin set” problem. I improved the problem
description and changed the program to list a sample solution for all of
the smaller sets of coins that can make change.
March 28, 2004:
I posted version 1 of a Drag
Colors Puzzle today. The idea is to guess a secret color pattern
generated by the program in the fewest number of guesses. The program is
classified at the Beginners level since it has less than 50 lines of user
written code. It's analogous to Mastermind,
except the only feedback given is the number of colors in the correct position.
It seems that this makes the game more difficult to analyze, at least I haven't
been successful so far. I suspect that similar pattern guessing games must
have been analyzed and documented under other names.
Let
me know if you locate or develop an optimum guessing strategy just to put me
out of my misery. (This version has pattern of 3 colors
chosen from a palette of 4 colors - an analysis would derive the best
strategy for patterns of length M chosen from N colors. Seemingly not a
trivial exercise.)
March 29, 2004:
While proving to James the other day that there were really 293 ways to make
change for a dollar, I needed to resort my output grid in descending order to
match his format. Here is an update to the Grid
Quicksort program that will sort string grid columns in ascending or
descending sequence. (By the way, he had missed the 4 ways to make change
that have more than 2 quarters.)
April 2, 2004:
I decided to provide a print feature in my current puzzle project (Scrambled
Pie) and to print the solution upside-down at the bottom of the page.
Using the "divide and conquer" strategy for problem solving, it seemed
worthwhile to develop the inverted display and print code first. Here is Test
Inverted Text in the Delphi-Techniques section.
I included a runtime fix for a Delphi 5
"bug" along the way - "hard" line breaks are
inserted into memo text at design time. Guess I should go
check D7 and see if the problem still exists. But maybe if I procrastinate
a while, some alert Delphian will send me feedback.
April
7, 2004: Here's a Scrambled
Pie puzzle generator/solver. Given four words, all missing the same
single letter, find the letter and unscramble the words. Mensa® Calendar
owners will already have struggled with these. The program will generate
puzzles simple enough for me to solve up to those that I would think are nearly
impossible. And some, like the sample shown here,
look simple but may be tough.
April
16, 2004: One of the neat
things about running this website is hearing from people around the world.
While I was busy hiding and (and finding) Easter eggs this week, an email came
in from a German fellow who is teaching English in China! He's
using the Scrolling
LEDs program to present vocabulary but wondered if the program could be
modified to save his font and text settings from run to run. Sure -
it's done Hans!
April
25, 2004: This week's
offering is the Missionaries
and Cannibals river crossing puzzle. (That name is more popular
than "Cannibals and Missionaries" by about a 3 to 2 margin
according to Google.) No animated graphics, but it does allow
user play and of course the program can find all 4 solutions in a few
milliseconds.
May
2, 2004: My version of the
classical pattern guessing game, Mastermind,
has been downloaded a couple of thousand times since I posted it three
years ago. The objective for the code-breaker is to identify a
secret peg pattern using clues provided by the code-maker. Either the user
or the program may play the code-breaker role. The user is the code
breaker in this screenshot (and is about
win!)
Based on user feedback, I updated
the program this week to allow user selection of number of pegs and colors and
increased the maximum number of pegs in the secret pattern to 6.
Surprisingly, the 5 or 6 peg case seems only slightly more difficult than
with 4 pegs. The program must work considerably harder, however,
to analyze 46,000 potential secret patterns instead of 1200!
May 7, 2004:
A viewer found a small problem in the Minimize
to Systray demo program posted in Delphi-Techniques this week.
The demo shows how to minimize programs to an icon the "System
Notification Area" rather than the taskbar. I've
corrected a problem with "cannot
switch sheets on a tabbed PageControl after restore from Systray"
. Writing the one line of code to fix it took about 5 seconds - finding
which line to write took about 5 hours!
I'm receiving about 5 emails per day now
with virus attachments. The bodies have messages like "Important
informations!” or "Don't visit these web sites"
and often include reassurances like "Virus scanned and safe to open".
Right! Maybe we should thank the virus senders for educating the public on
the importance of acquiring a virus scan program and keeping it and Windows
updated. Microsoft says that 1.5 million copies of their "Sasser Worm
Removal" tool have been downloaded, so there's 1.5 million users who have
probably turned on Windows automatic update to keep it from happening again.
Seems like virus writers, "script kitties", and hackers would be
putting themselves out of business before long.
Spam is of course the
other daily annoyance - I get 20 or so offers per day to refinance my
house or buy drugs without a prescription or to enlarge some body part.
I'm sure that my spam load is minor compared to many, but it has bugged me.
I have a 30-day trial of "I HATE SPAM" installed now, and it looks
like it will be worth the $20 cost. Here's a
link to a review of several "Spam Filters" from the current PC World
magazine.
By the way, the PC World site will
put some "spyware" on your system. Get freeware program
"SpyBot" to get rid of it and immunize against future infestations. Don't
worry to much about this - if you have Spybot, you are immunized against it, if
you don't have SpyBot, you already have dozens or hundreds of spyware programs
running on your system. Here's a Microsoft
link explaining more and recommending SpyBot or Ad-aware software as
solutions.
Gary Darby
http://www.delphiforfun.org/
" Even
if you're on the right track, you'll get run over if you just sit there."
- Will Rogers
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