Merge pull request #5876 from ccntrq/challenge-158

Add solutions for challenge 158

2 files changed, 75 insertions, 0 deletions

diff --git a/challenge-158/alexander-pankoff/perl/ch-1.pl b/challenge-158/alexander-pankoff/perl/ch-1.pl
new file mode 100755
index 0000000000..5818eb641e
--- /dev/null
+++ b/challenge-158/alexander-pankoff/perl/ch-1.pl
@@ -0,0 +1,34 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use feature qw'say state signatures';
+no warnings qw'experimental::signatures';
+
+use List::Util qw(sum0);
+
+run() unless caller();
+
+sub run() {
+    say join( ', ', additive_primes() );
+}
+
+sub additive_primes($max = 100) {
+    return grep { is_prime($_) && is_prime( digit_sum($_) ) } 2 .. $max;
+}
+
+# from challenge 150 task 2
+sub is_prime($x) {
+    return 0 if $x <= 1;
+    return 1 if $x <= 3;
+    for ( my $i = 2 ; $i <= sqrt($x) ; $i++ ) {
+        return 0 if $x % $i == 0;
+    }
+    return 1;
+}
+
+# from challenge 149 task 1
+sub digit_sum($x) {
+    my $sum = sum0 split( '', $x );
+
+    return $sum;
+}
diff --git a/challenge-158/alexander-pankoff/perl/ch-2.pl b/challenge-158/alexander-pankoff/perl/ch-2.pl
new file mode 100755
index 0000000000..b672d273e5
--- /dev/null
+++ b/challenge-158/alexander-pankoff/perl/ch-2.pl
@@ -0,0 +1,41 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use feature qw'say state signatures';
+no warnings qw'experimental::signatures';
+
+run() unless caller();
+
+sub run() {
+
+    say join( ', ', cuban_primes() );
+
+}
+
+sub cuban_primes($max = 1000) {
+
+    my @cubans    = ();
+    my $i         = 1;
+    my $candidate = 0;
+    while ( $candidate <= $max ) {
+        $candidate = centered_hexagonal_number($i);
+        push @cubans, $candidate if is_prime($candidate);
+        $i += 1;
+    }
+    return @cubans;
+
+}
+
+# from challenge 150 task 2
+sub is_prime($x) {
+    return 0 if $x <= 1;
+    return 1 if $x <= 3;
+    for ( my $i = 2 ; $i <= sqrt($x) ; $i++ ) {
+        return 0 if $x % $i == 0;
+    }
+    return 1;
+}
+
+sub centered_hexagonal_number($y) {
+    return 3 * $y * $y + 3 * $y + 1;
+}