in reply to Re^2: mem usage
in thread mem usage

You can trim your shuffle a little by omitting the line:         next if $i==$j;.

Swapping an item with itself doesn't affect the algorithm's fairness, and doing it once costs less, than testing n times and avoiding it once.

And you save a little more by avoiding the list assignment: 

my $tmp = $array[ $i ]; 
$array[ $i ] = $array[ $j ]; 
$array[ $j ] = $tmp;

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Doesn't look as nice though.

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Re^4: mem usage
by ikegami (Patriarch) on May 26, 2010 at 19:46 UTC
    Including cleaning up the counter, 
    sub shuffle {
    my $array = shift;
    my $i = @$array;
    while ($i) {
        my $j = int rand($i--);
        my $t = $array->[$i];
        $array->[$i] = $array->[$j];
        $array->[$j] = $t;
    }
}

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[d/l]
Re^4: mem usage
by halfcountplus (Hermit) on May 26, 2010 at 19:36 UTC
    You can trim your shuffle a little by omitting the line: next if $i==$j;

    Good point!
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