[JOB] Perl Software Developer and Database programmer

[Dirk Koopman]

On Wed, 2006-02-22 at 08:10 -0800, Ovid wrote:
> As a thoroughly depressing example, here's a sample question I throw at
> people who apply for Perl jobs:
> 
>   Imagine we're building an app and it turns out to be slow.  We've
>   profiled the code and reduced the problem down to this:
> 
>     foreach my $alpha ( @alphas ) {
>         foreach my $beta ( @betas ) {
>             if ( $alpha == $beta ) {
>                 push @results, $beta;
>             }
>         }
>     }
> 
>   1.  What is a likely reason for the performance problem?
>   2.  How might we speed it up?

> Heck, if you've never used Perl, the problem itself should be clear,
> even if a "Perlish" solution is not (sort @betas and do a binary
> search, anyone?)
> 

Ok I'll bite (I'm bored waiting for Airwave to sort their network out).

How about:

my @beta = (1,3,5,6,7,9);
my @alpha = (2,3,4,8,9,10);

my %beta;

@beta{@beta} = ();
my @results = grep {exists $beta{$_}} @alpha;

print join(',', @results), "\n";


Dirk