August 31, 2001: A Delphi Topics page was
posted a while back showing how to sort a StringGrid on any
column. The simple sort used there was fine for a demo with a
few rows - not so good when I tried it on a 10,000 row grid
recently. Here's a page with a StringGrid
version that will do the job in a few seconds instead of
minutes or hours. The application, by the way, is a booklist browser
for the Accelerated Reader program used in a number of schools these days
(including the school of one of my three precocious [and
precious] granddaughters). A Web-based version is next - I'll
keep you posted.
August 30, 2001: I'm back! Two more
weeks of entertaining grandkids was time well spent. But
they're all back in school now, so I guess it's time for me to get back to
work too. I just saw that Borland is offering a
free
download of Delphi 6 Personal!, in exchange for answering some survey
questions - sounds like a fair exchange to me. Not
surprisingly, the actual download link seems to be overloaded right now -
but sometime in the next week or two you should be able to get a
copy. Be warned, it looks like it's a 140mb download.
August 14:2001: I replaced version 1 of
Peg Solitaire with version 2 - the
user can actually make moves and try to solve the puzzles
now. For programmers - standard drag cursors
have been by customized versions. Creating customized cursors
is worthy of a Delphi-Techniques page. Stay
tuned.
By the way, Plus and Cross are the
names of two of the solitaire board configurations solved here - which
reminds me of a story about the youngster who was getting poor grades in
mathematics. His parents finally transferred him to a Catholic
school and saw his math grades go to straight A's . When asked what
triggered the improvement, the boy said "When I walked in the first
day and saw that guy nailed to the plus sign, I knew they were
really serious about math and it was time to shape
up!'
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Diamond |
Fireplace |
August 10, 2001:
Here's version 1 of a Peg Solitaire
game. I guess this version, in which the program does all of
solving isn't exactly a game. More an example of the power of a
simple depth first search to solve a problem.
We can search about half a million board positions per second and
surprisingly the
typical problem is solved in only a couple of million position
searches. Surprising because the number of board potential
positions even for "Fireplace" is around 40 million and
for "Diamond" is around 1027.
Fortunately the number of positions actually reachable seems to be much
smaller. Those two configurations are among the seven
common initial configurations
solved by this version. Oh yeah, there's also an
animated playback of the solution once we find it.
In case you're not familiar with the game, the objective
is to remove pegs by jumping them with another peg until the last peg is
left in the center hole.
Version 2 with user play, (more fun for the user,
but less fun for the programmer) will be along shortly.
August 6, 2001: Fibonacci was probably the
greatest mathematician of the 13th century - his works were instrumental
in converting Europe from the Roman numbers to the Hindu-Arabic
system. His name is most commonly associated with the series
of numbers formed by starting with 0 and 1 and then creating the rest of the
series by adding the two prior members. What's amazing is
that this series approximates the Golden ratio which
frequently appears in nature including the arrangement of seeds in
sunflower heads. (In the image at left the apparent overlapping seed
spirals have 34 arms in one direction and 55 in the other, the 10th and
11th Fibonacci numbers.) Here's more of the story and a
simple Delphi program that draws Fibonacci
Sunflowers.
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