Merge pull request #5693 from choroba/ech153

Add solutions to 153: Left Factorials & Factorions by E. Choroba

2 files changed, 78 insertions, 0 deletions

diff --git a/challenge-153/e-choroba/perl/ch-1.pl b/challenge-153/e-choroba/perl/ch-1.pl
new file mode 100755
index 0000000000..a3797d8fd2
--- /dev/null
+++ b/challenge-153/e-choroba/perl/ch-1.pl
@@ -0,0 +1,56 @@
+#!/usr/bin/perl
+use warnings;
+use strict;
+
+use experimental 'signatures';
+
+use List::Util qw{ sum product };
+
+sub factorial ($n) {
+    product(1, 1 .. $n)
+}
+
+sub left_factorial ($n) {
+    sum(map factorial($_), 0 .. $n - 1)
+}
+
+{   my %F;
+    sub factorial_m ($n) {
+        $F{$n} //= product(1, 1 .. $n)
+    }
+}
+
+{   my %LF = (1 => 1);
+    sub left_factorial_m ($n) {
+        $LF{$n} //= left_factorial_m($n - 1) + factorial_m($n - 1)
+    }
+}
+
+use Test::More tests => 22;
+
+is left_factorial(1), 1;
+is left_factorial(2), 2;
+is left_factorial(3), 4;
+is left_factorial(4), 10;
+is left_factorial(5), 34;
+is left_factorial(6), 154;
+is left_factorial(7), 874;
+is left_factorial(8), 5914;
+is left_factorial(9), 46234;
+is left_factorial(10), 409114;
+
+is left_factorial(20), 128425485935180314;
+
+is left_factorial_m($_), left_factorial($_) for 1 .. 10, 20;
+
+use Benchmark qw{ cmpthese };
+cmpthese(-3, {
+    plain    => 'left_factorial(10)',
+    memoized => 'left_factorial_m(10)',
+});
+
+__END__
+
+              Rate    plain memoized
+plain     332153/s       --     -96%
+memoized 9473789/s    2752%       --
diff --git a/challenge-153/e-choroba/perl/ch-2.pl b/challenge-153/e-choroba/perl/ch-2.pl
new file mode 100755
index 0000000000..d091c506c1
--- /dev/null
+++ b/challenge-153/e-choroba/perl/ch-2.pl
@@ -0,0 +1,22 @@
+#!/usr/bin/perl
+use warnings;
+use strict;
+use experimental 'signatures';
+
+use List::Util qw{ sum };
+
+{   my %factorial = (0 => 1);
+    $factorial{$_} = $factorial{ $_ - 1 } * $_ for 1 .. 10;
+
+    sub is_factorion ($n) {
+        sum(@factorial{ split //, $n }) == $n
+    }
+}
+
+use Test::More tests => 5;
+
+ok is_factorion(1);
+ok is_factorion(2);
+ok is_factorion(145);
+ok is_factorion(40585);
+ok ! is_factorion(125);