Update ch-1.pl

Iterate primorial numbers to find the first Euclid number that is not prime.

1 files changed, 16 insertions, 0 deletions

diff --git a/challenge-012/jaime/perl5/ch-1.pl b/challenge-012/jaime/perl5/ch-1.pl
index 3ecead2762..935c585fd5 100644
--- a/challenge-012/jaime/perl5/ch-1.pl
+++ b/challenge-012/jaime/perl5/ch-1.pl
@@ -6,3 +6,19 @@
 # primes are called the Euclid Numbers (see wiki). Write a script that
 # finds the smallest Euclid Number that is not prime.
 
+sub is_prime { # is a given positive integer an odd prime?
+    my ($n) = @_;
+    for (my $i = 3; $i < $n; $i += 2) { # determine if odd number is prime.
+	return 0 unless $n % $i;
+    }
+    return 1; # odd number is prime.
+}
+
+my $p = 2; # start with second primorial
+for (my $i = 3; ;$i += 2) {
+    next unless is_prime $i;
+    $p *= $i; # next primorial
+    last unless is_prime 1+$p;
+}
+
+print 1+$p;