Week 168 First commit

2 files changed, 92 insertions, 0 deletions

diff --git a/challenge-168/cheok-yin-fung/perl/ch-1.pl b/challenge-168/cheok-yin-fung/perl/ch-1.pl
new file mode 100644
index 0000000000..61ba32d69e
--- /dev/null
+++ b/challenge-168/cheok-yin-fung/perl/ch-1.pl
@@ -0,0 +1,33 @@
+#!/usr/bin/perl
+# The Weekly Challenge 168
+# Task 1 Perrin Prime 
+use v5.24.0;
+use warnings;
+use List::Util qw/reduce none/;
+use Math::BigInt::GMP;          # [remark]
+use Math::BigInt::Pari;         # [remark]
+use Math::Prime::Util::GMP qw/is_prime next_prime/;
+use bigint try => 'GMP,Pari';   # [remark]
+# remark: follow suggestions on POD of Math::Prime::Util
+
+my @perrin_primes = (2,3);
+my ($ppnm3,$ppnm2,$ppnm1, $ppn) = (3,0,2,3);
+
+while (scalar @perrin_primes < 13) {
+    if (is_prime($ppn) == 2) {
+        push @perrin_primes, $ppn if none {$_ == $ppn} @perrin_primes;
+        say $ppn;
+    }
+    $ppnm3 = $ppnm2;
+    $ppnm2 = $ppnm1;
+    $ppnm1 = $ppn;
+    $ppn = $ppnm2 + $ppnm3;
+}
+
+say join ", ", @perrin_primes;
+
+# time: 
+# real	0m0.078s
+# user	0m0.056s
+# sys	0m0.008s
+
diff --git a/challenge-168/cheok-yin-fung/perl/ch-2.pl b/challenge-168/cheok-yin-fung/perl/ch-2.pl
new file mode 100644
index 0000000000..0518d1dbcd
--- /dev/null
+++ b/challenge-168/cheok-yin-fung/perl/ch-2.pl
@@ -0,0 +1,59 @@
+#!/usr/bin/perl
+# The Weekly Challenge 168
+# Task 2 Home Prime 
+# Usage: ch-2.pl [integer > 1]
+use v5.24.0;
+use warnings;
+use List::Util qw/reduce/;
+use Math::BigInt::GMP;          # [remark]
+use Math::BigInt::Pari;         # [remark]
+use Math::Prime::Util::GMP qw/is_prime next_prime/;
+use bigint try => 'GMP,Pari';   # [remark]
+# remark: follow suggestions on POD of Math::Prime::Util
+
+
+say hp($ARGV[0]) if defined($ARGV[0]);
+
+
+
+sub hp {
+    my_hp($_[0],0);
+}
+
+
+
+sub my_hp {
+    my $recur_depth = $_[1];
+
+    die "Walk so far but still cannot get result. :(\n" if $recur_depth > 10;
+    my $num = $_[0];
+    if (is_prime($num) == 2) {
+        return $num;
+    }
+
+    my @factors = ();
+    my $p = 2;
+    do {
+        if (!($num % $p)) {
+            push @factors, $p;
+            $num /= $p;
+        }
+        else {
+            $p = next_prime($p);
+        }
+    } while ($num != 1);
+    my $nxt = (reduce { $a . $b } @factors);
+    say "  $nxt";
+    return my_hp($nxt, ++$recur_depth);
+}
+
+use Test::More tests => 5;
+# test data from OEIS
+ok hp(10) == 773;
+ok hp(24) == 331_319;
+ok hp(32) == 241_271;
+ok hp(45) == 3_411_949;
+
+ok hp(44) == 22815088913;  # this test spends approx 0.5 min (on CY's laptop).
+
+# ok hp(40) == 3314192745739;  # this test spends approx. 2 min.