Merge pull request #6207 from choroba/ech167

Add solutions to 167: Circular Prime & Gamma Function by E. Choroba

2 files changed, 64 insertions, 0 deletions

diff --git a/challenge-167/e-choroba/perl/ch-1.pl b/challenge-167/e-choroba/perl/ch-1.pl
new file mode 100755
index 0000000000..c255908376
--- /dev/null
+++ b/challenge-167/e-choroba/perl/ch-1.pl
@@ -0,0 +1,45 @@
+#!/usr/bin/perl
+use warnings;
+use strict;
+
+use Math::Prime::Util qw{ next_prime is_prime };
+
+sub is_circular {
+    my ($p) = @_;
+    my $c = $p;
+
+    # Start from 2, we don't need to check the number itself.
+    for (2 .. length $p) {
+        substr $c, 0, 0, substr $c, -1, 1, "";
+        return if $c < $p || ! is_prime($c);
+    }
+    return 1
+}
+
+sub circular_prime {
+    my ($tally, $min_digits) = @_;
+    my @primes;
+    my $from = '1' x $min_digits - 1;
+    my $p = next_prime($from);
+    while (@primes < $tally) {
+        push @primes, $p
+            if ($p < 10 || $p !~ /[024568]/)  # This speeds the code slightly.
+            && is_circular($p);
+        $p = next_prime($p);
+    }
+    return \@primes
+}
+
+use Test::More tests => 3;
+
+is_deeply circular_prime(10, 3),
+    [113, 197, 199, 337, 1193, 3779, 11939, 19937, 193939, 199933],
+    'Example';
+
+is_deeply circular_prime(10, 1),
+    [2, 3, 5, 7, 11, 13, 17, 37, 79, 113],
+    'Shorter CPs';
+
+is_deeply circular_prime(1, 19),
+    [1111111111111111111],
+    'Longer CP';
diff --git a/challenge-167/e-choroba/perl/ch-2.pl b/challenge-167/e-choroba/perl/ch-2.pl
new file mode 100755
index 0000000000..0de3775583
--- /dev/null
+++ b/challenge-167/e-choroba/perl/ch-2.pl
@@ -0,0 +1,19 @@
+#!/usr/bin/perl
+use warnings;
+use strict;
+
+use PDL;
+use PDL::GSLSF::GAMMA;
+
+sub gamma {
+    unpdl((gsl_sf_gamma(shift))[0])->[0]
+}
+
+use Test2::V0 qw{ is plan within };
+plan 3;
+
+my $TOLERANCE = 0.0100000000001;
+
+is gamma(3), within(1.99, $TOLERANCE);
+is gamma(5), within(24);
+is gamma(7), within(719.99, $TOLERANCE);