TedPride,
This is blazingly fast...
I wanted to see just how fast, so I modified your code to fit into the benchmark FoxtrotUniform and I were playing with. It turns out your code is only about half as fast as my second version and it has a bug I didn't bother to track down. To see the bug, try entering 3133756 with your code.
I say your code is only about half as fast because it got less than halfway through (line 2235 of 5000) when it blew up and it took approximately the same amount of time (3.619 seconds) to get there.
In case you want to run some more tests yourself, take a look at gen_targets.pl and then use this modified code:
#!/usr/bin/perl
use strict;
use warnings;
my ($i, $j, $inum, $jnum, $left);
my $file = $ARGV[0] || 'targets.txt';
open (INPUT, '<', $file) or die "Unable to open $file for reading : $!
+";
while ( chomp( my $inp = <INPUT> ) ) {
BING:
for ($i = tget($inp); $i; $i--) {
$inum = tmake($i);
$left = tget($inp - $inum - 1) + 1;
for ($j = 1; $j < $left; $j++) {
$jnum = tmake($j);
last BING if (tis($inp - $inum - $jnum));
}
}
}
sub tget { return int(sqrt(1 + $_[0] * 2) - .5); }
sub tmake { return (.5 * $_[0] * ($_[0] + 1)); }
sub tis { my $n = shift; return ($n == tmake(tget($n))); }
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.
|