Merge pull request #6242 from E7-87-83/newt

Week 168 Submission

2 files changed, 101 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..faf90a9bb3
--- /dev/null
+++ b/challenge-168/cheok-yin-fung/perl/ch-1.pl
@@ -0,0 +1,29 @@
+#!/usr/bin/perl
+# The Weekly Challenge 168
+# Task 1 Perrin Prime 
+use v5.24.0;
+use warnings;
+use List::Util qw/none/;
+use Math::Prime::Util qw/is_prime/;
+
+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 + $ppnm3;
+}
+
+say join ", ", @perrin_primes;
+
+# time: 
+# real	0m0.025s
+# user	0m0.017s
+# sys	0m0.009s
+
diff --git a/challenge-168/cheok-yin-fung/perl/ch-2.pl b/challenge-168/cheok-yin-fung/perl/ch-2.pl
new file mode 100644
index 0000000000..00406d25ef
--- /dev/null
+++ b/challenge-168/cheok-yin-fung/perl/ch-2.pl
@@ -0,0 +1,72 @@
+#!/usr/bin/perl
+# The Weekly Challenge 168
+# Task 2 Home Prime 
+# Usage: ch-2.pl [integer > 1]
+use v5.24.0;
+use warnings;
+use Math::Prime::Util qw/is_prime next_prime/;
+use Math::BigInt;
+
+say hp($ARGV[0]) if defined($ARGV[0]) && $ARGV[0] != 1;
+
+
+
+sub hp {
+    my_hp($_[0],0);
+}
+
+
+
+sub my_hp {
+    my $num = $_[0];
+    my $recur_depth = $_[1];
+    die "Number involved too large.\n" 
+        if  
+            Math::BigInt->new("18446744073709551616") # 2**64
+                        ->ble( Math::BigInt->new($num) );
+    
+
+    if (is_prime($num) == 2) {
+        return $num;
+    }
+
+    die "Walk so far but still cannot get result. :(\n" if $recur_depth > 20;
+
+    my @factors = ();
+    my $p = 2;
+    while ($num != 1) {
+        if (!($num % $p)) {
+            push @factors, $p;
+            $num /= $p;
+        }
+        else {
+            $p = next_prime($p);
+        }
+        if ($p > sqrt $num) {
+            say "useful";
+            push @factors, $num;
+            last;
+        }
+    }
+    my $nxt = join "", @factors;
+    say "  $nxt";
+    return my_hp($nxt, ++$recur_depth);
+}
+
+use Test::More tests => 8;
+# test data from OEIS
+ok hp(10) == 773;
+ok hp(24) == 331_319;
+ok hp(32) == 241_271;
+ok hp(40) == 3314192745739;  
+ok hp(44) == 22815088913;  
+ok hp(45) == 3_411_949;
+
+# bigger cases;
+ok hp( 8) == 3331113965338635107;
+ok hp(20) == 3318308475676071413;
+
+# real	0m5.553s
+# user	0m5.535s
+# sys	0m0.016s
+