You’re right, using a hash is, in general, a better approach than using an array, because a hash is, by its nature, optimised for lookup.

There’s a useful discussion of the various options in perlfaq4#How-can-I-tell-whether-a-certain-element-is-contained-in-a-list-or-array?

In fact the usefull discussion suggested by Athanasius tell us to use the smart match operator ~~

My benchmarks (tell if i'm wrong) tell us the same: the smart match operator is the fastest.


use strict;
use warnings;
use Benchmark qw(cmpthese timethese);
use 5.010;
use List::Util qw(any);

my $search = $ARGV[0]||'perlaceo';
my $file = $ARGV[1]||'enwiktionary-latest-all-titles-in-ns0';
die unless $file;
my @lines;
open my $fh,'<',$file or die "Unable to open $file";
@lines = <$fh>;
print "\nFILE: $file\nARRAY ELEMENTS: ",
      scalar @lines," (read in ",(time - $^T),
      " seconds).\n\n";

my $iterations = -3;
######################################################################
+##########
my $name1 = "Plain array lookup"; #
my $code1 = <<'END_CODE1';
     for(@lines){ last if $_ eq $search }
END_CODE1
######################################################################
+##########
my $name2 = "List::Util any    "; #
my $code2 = <<'END_CODE2';
     any { $_ eq $search } @lines;
END_CODE2
######################################################################
+##########
my $name3 = "smart match ~~    "; #
my $code3 = <<'END_CODE3';
   $search ~~ @lines;
END_CODE3
######################################################################
+##########
my $results = timethese($iterations, {  $name1 => $code1,
                                        $name2 => $code2,
                                        $name3 => $code3
                                      } ) ;
print "\n\n";
cmpthese( $results );
[download]

here my results:



FILE: cat.txt
ARRAY ELEMENTS: 3 (read in 0 seconds).
                        Rate List::Util any     Plain array lookup sma
+rt match ~~
List::Util any     2548237/s                 --               -38%    
+           -62%
Plain array lookup 4105378/s                61%                 --    
+           -38%
smart match ~~     6655789/s               161%                62%    
+             --



FILE: HOSTS-zero-tollerance.txt
ARRAY ELEMENTS: 10605 (read in 0 seconds).
                        Rate List::Util any     Plain array lookup sma
+rt match ~~
List::Util any     2599992/s                 --               -41%    
+           -62%
Plain array lookup 4437049/s                71%                 --    
+           -36%
smart match ~~     6879527/s               165%                55%    
+             --



FILE: 02packages.details.txt
ARRAY ELEMENTS: 165584 (read in 2 seconds).
                        Rate List::Util any     Plain array lookup sma
+rt match ~~
List::Util any     2481882/s                 --               -46%    
+           -61%
Plain array lookup 4556540/s                84%                 --    
+           -28%
smart match ~~     6362283/s               156%                40%    
+             --



FILE: enwiktionary-latest-all-titles-in-ns0
ARRAY ELEMENTS: 4316483 (read in 91 seconds).
                        Rate List::Util any     Plain array lookup sma
+rt match ~~
List::Util any     2565579/s                 --               -44%    
+           -63%
Plain array lookup 4621251/s                80%                 --    
+           -34%
smart match ~~     6972221/s               172%                51%    
+             --
[download]


L*

There are no rules, there are no thumbs..
Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.

Right track, but still too much work being done in the loop!

my @choices = qw/Apple Banana Tiger Lion Cat Turtle/;
my @Single = qw/Apple Turtle/;
my @Double = qw/Lion/;
my %flags =
   ( map { $_ => 1 } @Single ),
   ( map { $_ => 2 } @Double );

for my $choice (@choices) {
    my $flag = $flags{$choice} || 0;
    print "$choice => $flag\n";
}
[download]

Yes, that will work if @Single and @Double aren't allowed to share any elements...