Sorting is an O(n log n) operation. Testing a list for sortedness is an O(n) operation. Test first, then sort if necessary.
use strict;
use warnings;
use List::Util qw( first );
my @x = qw( 1 3 2 4 5 );
if( defined first { $x[$_] > $x[$_+1] } 0 .. $#x - 1 ) {
@x = sort { $a <=> $b } @x;
}
Strategies for testing whether a change has been made after sorting has been applied will either involve a checksum of some type (ie, take an MD5 of the list's contents before and again after), or keeping a copy of the pre-sorted list for comparison. One way you're throwing CPU cycles at the problem, and the other way, you're throwing memory at it. If you can just check whether sorting is necessary ahead of time, you conserve both.
-
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.
|