use strict;

use Benchmark 'cmpthese';

my $SQUARE;
my $MAX_NUMBER = 1000;
foreach my $number (4..$MAX_NUMBER) {
  my $square  = $number * $number;
  $SQUARE->{$square} = 1;
}
my $string = q(59738219024971503664);

cmpthese ( -1, {
                orig => \&orig,
                indx => \&windex
               }
         );

sub orig {
  my $total_length = 0;
  foreach my $square (keys %{$SQUARE}) {
    if ($string =~ /$square/) {
      my $length =  length($square);
      $total_length  += $length;
    }
  }
  return $total_length;
}

sub windex {
  my $string = q(59738219024971503664);
  my $total_length = 0;
  foreach my $square (keys %{$SQUARE}) {
    if ( index( $string, $square ) > -1 ) {
      my $length =  length($square);
      $total_length  += $length;
    }
  }
  return $total_length;
}
__END__
% perl sqs.pl
        Rate orig indx
orig 100.0/s   -- -91%
indx  1067/s 967%   --