Posted by Tom Moertel
Thu, 23 Mar 2006 21:51:00 GMT
I ran across a fun programming puzzle (via
Raganwald):
Given a deck of n unique cards, cut the deck i cards from top
and perform a perfect shuffle. A perfect shuffle begins by putting
down the bottom card from the top portion of the deck followed by
the bottom card from the bottom portion of the deck followed by
the next card from the top portion, etc., alternating cards until
one portion is used up. The remaining cards go on top. The problem
is to find the number of perfect shuffles required to return the
deck to its original order. Your function should be declared as:
static long shuffles(int nCards,int iCut);
Please send the result of shuffles(1002,101) along with your
program and your resume to ‘resume’ at nextag.com.
It’s a fun problem, so give it a try before reading on.
Warning: small spoilers ahead
Read more...
Posted in programming, haskell, fun stuff
Tags haskell, puzzles, shuffles
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Posted by Tom Moertel
Tue, 14 Mar 2006 22:39:00 GMT
Last week I gave a brief talk for the Pittsburgh Perl
Mongers about embedding domain-specific languages
into Perl. The slides from the talk are now available:
Embedding an XHTML template language into Perl.
Posted in programming languages, perl, talks
Tags dsls, perl, pghpm, talks
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Posted by Tom Moertel
Fri, 03 Mar 2006 15:13:00 GMT
It’s a real forehead-slapper that I only now started using Tab Mix Plus, a
Firefox Extension that lets you completely customize
Firefox’s tab behavior.
It has about a billion settings, but the defaults are carefully chosen
so that it does good stuff without needing adjustment.
Unless you’re a goofball, you will notice an immediate improvement in
browsing.
Among the more useful features are:
- Session management – If you quit Firefox (or it crashes), Tab Mix
Plus can restore your session when you restart.
- Sensible forking – If you “fork” a tab, the new tab appears next
to its parent, not at the end of the tab bar. As a result, related
tabs are clustered, not scattered, and the ordering of tabs
corresponds with your brain’s picture of the session. (Also, you
can drag tabs, should you want to impose another ordering.)
- I’m-new highlights – Tabs you fork into the background are
highlighted to let you know they contain new, unseen content. This is
great for power sessions when you otherwise couldn’t remember which
tabs you’ve already seen.
- Locking/Protecting – Lock a tab, and the browser won’t change it.
If you click a link or do anything else that would replace the
contents of the tab, it will fork a new tab instead. Protect a tab,
and you can’t accidentally close it; you must unprotect it first.
If you use Firefox, you need to check
out Tab Mix Plus. It’s good stuff.
Posted in good stuff
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Posted by Tom Moertel
Wed, 01 Mar 2006 20:17:00 GMT
While we read, our minds subconsciously correct mistakes and overlook omissions in the steam of words we see, especially when reading familiar texts. This mental feature, which allows us to skim long documents, has a nasty drawback when we are writing: it makes it our own mistakes harder to spot.
One of the most common writing mistakes that our brains stealthily correct is the the duplicate word problem. For example, I inserted a double the into the previous sentence. Did you catch it?
If so, don’t be too proud of your accomplishment. It is easier to see errors in others’ writing than in your own. Your brain is attuned to your natural writing patterns and much more likely to repair your mistakes without your knowing.
To overcome this problem, some writers recommend reading your work backward, but I think computers are a more practical solution.
Here’s the Perl script that I use to spot duplicate words:
#!/usr/bin/perl -n00
# dupwords.pl - find duplicate words in the input stream
print "$ARGV: para $.: ($1)\n"
while /(\b(\w+)\b\s+\b\2\b)/sg;
I use this script from Emacs via shell-command-on-region. I also use it from the command line to find duplicate-word errors in batch:
find . -name '*.txt' | xargs dupwords.pl
The duplicate-words problem is a favorite for programming cookbooks, so if you don’t like my recipe (or Perl), you have many other options.
Posted in perl, writing
Tags perl, tools, writing
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