Merge remote-tracking branch 'upstream/master'

3 files changed, 118 insertions, 0 deletions

diff --git a/challenge-147/steven-wilson/javascript/ch-2.js b/challenge-147/steven-wilson/javascript/ch-2.js
new file mode 100755
index 0000000000..36fadd5903
--- /dev/null
+++ b/challenge-147/steven-wilson/javascript/ch-2.js
@@ -0,0 +1,38 @@
+#!/usr/bin/env node
+// Week 147 Task 2
+// Pentagon Numbers
+// Write a sript to find the first pair of Pentagon Numbers
+// whose sum and difference are also a Pentagon Number.
+// Answer: First pair is 1560090 and 7042750
+
+var pentagonal_numbers = [1]
+var pair_found = false
+var number = 2
+
+while (!pair_found) {
+	let next_pn = pentagonal_number(number)
+	for (let i = 0; i < pentagonal_numbers.length; i++) {
+		if ((is_pentagonal_number(next_pn - pentagonal_numbers[i])) && 
+			(is_pentagonal_number(next_pn + pentagonal_numbers[i]))) {
+			console.log('First pair are ' + pentagonal_numbers[i] + ' and ' + next_pn)
+			pair_found = true
+			break
+		}
+	}
+	pentagonal_numbers.push(next_pn)
+	number++
+}
+
+function pentagonal_number (number) {
+	return ( ( 3 * ( number * number ) ) - number ) / 2
+}
+
+function is_pentagonal_number (number) {
+	let remainder = ( Math.sqrt( 24 * number + 1 ) + 1 ) % 6;
+    if ( remainder > 0 ) {
+    	return false
+    }
+    else {
+    	return true
+    }
+}
diff --git a/challenge-147/steven-wilson/perl/ch-1.pl b/challenge-147/steven-wilson/perl/ch-1.pl
new file mode 100644
index 0000000000..ceefab2a3d
--- /dev/null
+++ b/challenge-147/steven-wilson/perl/ch-1.pl
@@ -0,0 +1,39 @@
+#!/usr/bin/env perl
+# Week 147 Task 1
+# Truncatable Prime
+# Write a script to generate first 20 left-truncatable prime numbers in base 10.
+
+use strict;
+use warnings;
+use feature qw/ say /;
+use Math::Prime::Util qw/ next_prime is_prime /;
+
+my @ltp          = qw/ 2 /;
+my $prime_number = 2;
+
+while ( scalar @ltp < 20 ) {
+    $prime_number = next_prime($prime_number);
+    if ( is_truncatable_prime($prime_number) ) {
+        push @ltp, $prime_number;
+    }
+}
+
+sub is_truncatable_prime {
+    my $prime_number   = shift;
+    my $truncatable    = 1;
+    while ( length $prime_number > 0 ) {
+        if ( $prime_number =~ /0/ ) {    # contains no 0
+            $truncatable = 0;
+            last;
+        }
+        if ( not is_prime($prime_number) ) {
+            $truncatable = 0;
+            last;
+        }
+        $prime_number =~ /^[0-9]{1}([0-9]*)/;
+        $prime_number = $1;
+    }
+    return $truncatable;
+}
+
+say join " ", @ltp;
diff --git a/challenge-147/steven-wilson/perl/ch-2.pl b/challenge-147/steven-wilson/perl/ch-2.pl
new file mode 100644
index 0000000000..d1bf716a76
--- /dev/null
+++ b/challenge-147/steven-wilson/perl/ch-2.pl
@@ -0,0 +1,41 @@
+#!/usr/bin/env perl
+# Week 147 Task 2
+# Pentagon Numbers
+# Write a sript to find the first pair of Pentagon Numbers
+# whose sum and difference are also a Pentagon Number.
+# Answer: First pair is 1560090 and 7042750
+
+use strict;
+use warnings;
+use feature qw/ say /;
+use POSIX qw/ fmod /;
+
+my @pentagonal_numbers = qw/ 1 /;
+my $first_pair_found   = 0;
+my $number             = 2;
+
+while ( not $first_pair_found ) {
+    my $next_pn = pentagonal_number($number);
+    for (@pentagonal_numbers) {
+        if (    is_pentagonal_number( $next_pn - $_ )
+            and is_pentagonal_number( $next_pn + $_ ) )
+        {
+            say "First pair is $_ and $next_pn";
+            $first_pair_found = 1;
+            last;
+        }
+    }
+    push @pentagonal_numbers, $next_pn;
+    $number++;
+}
+
+sub pentagonal_number {
+    my $n = shift;
+    return ( ( 3 * ( $n * $n ) ) - $n ) / 2;
+}
+
+sub is_pentagonal_number {
+    my $x         = shift;
+    my $remainder = fmod( sqrt( 24 * $x + 1 ) + 1, 6 );
+    $remainder > 0 ? return 0 : return 1;
+}