euler35.pl

#!/usr/bin/perl -w
use strict;

my %primes = (
    '2' => 1,
    '3' => 1,
    '5' => 1,
    '7' => 1,
    '11' => 1,
    '13' => 1,
    '17' => 1,
    '19' => 1,
    '23' => 1,
    '29' => 1,
    '31' => 1,
    '37' => 1,
    '41' => 1,
    '43' => 1,
    '47' => 1,
    '53' => 1,
    '59' => 1,
    '61' => 1,
    '67' => 1,
    '71' => 1,
    '73' => 1,
    '79' => 1,
    '83' => 1,
    '89' => 1,
    '97' => 1,
);
my @primes=(sort {$a<=>$b} keys %primes);
sub isprime {
    my $num = shift;
    my $tmp = int(sqrt($num));
    foreach(@primes) {
        return 0 if ($num % $_ == 0);
        last if ($_>$tmp);
    }
    return 1;
}

sub iscircularprime {
    my $num = shift;
    foreach(2..length($num)) {
        $num =~ s/(\d)(.+)/$2$1/;
        return 0 unless (exists $primes{$num});
    }
    return 1;
}

foreach (100..1000000) {
    next if ($_%2 == 0);
    if (isprime($_)) {
        $primes{$_} = 1;
        push @primes, $_;
    } 
}

my $sum=0;
foreach (@primes) {
    $sum++ if iscircularprime($_);
}
print "$sum\n";