Merge pull request #5694 from wlmb/challenges

Solve PWC153

3 files changed, 54 insertions, 0 deletions

diff --git a/challenge-153/wlmb/blog.txt b/challenge-153/wlmb/blog.txt
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+++ b/challenge-153/wlmb/blog.txt
@@ -0,0 +1 @@
+https://wlmb.github.io/2022/02/21/PWC153/
diff --git a/challenge-153/wlmb/perl/ch-1.pl b/challenge-153/wlmb/perl/ch-1.pl
new file mode 100755
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+++ b/challenge-153/wlmb/perl/ch-1.pl
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+#!/usr/bin/env perl
+# Perl weekly challenge 153
+# Task 1: Left factorials
+#
+# See https://wlmb.github.io/2022/02/21/PWC153/#task-1-left-factorials
+use v5.12;
+use warnings;
+use Memoize;
+use bigint;
+use Text::Wrap qw(wrap $columns $break);
+
+memoize qw(left_factorial factorial);
+die "Usage: ./ch-1.pl N\nto get the first N left factorials" unless @ARGV;
+my $N=shift;
+$columns=62; $break=qr/\s/;
+say wrap("", "    ", "The first $N left factorials are: ",
+    join ", ", map {left_factorial($_)} (0..$N-1));
+sub left_factorial{
+    my $n=shift;
+    return factorial(0) if $n<=0;
+    return factorial($n)+left_factorial($n-1);
+}
+sub factorial{
+    my $k=shift;
+    return 1 if $k<=0;
+    return $k*factorial($k-1);
+}
diff --git a/challenge-153/wlmb/perl/ch-2.pl b/challenge-153/wlmb/perl/ch-2.pl
new file mode 100755
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+++ b/challenge-153/wlmb/perl/ch-2.pl
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+#!/usr/bin/env perl
+# Perl weekly challenge 153
+# Task 2: Factorions
+#
+# See https://wlmb.github.io/2022/02/21/PWC153/#task-2-factorions
+use v5.12;
+use warnings;
+use Memoize;
+use List::Util qw(sum0);
+memoize qw(factorial);
+die "Usage: ./ch-2.pl N1 N2...\nto test if Ni is factorion" unless @ARGV;
+foreach(@ARGV){
+    say("Expected a non-negative integer: $_"), next unless $_>=0;
+    my @digits=split '';
+    my @factorials=map {factorial($_)} @digits;
+    my $sum=sum0(@factorials);
+    my $factorion=$sum==$_;
+    say "$_ is", $factorion?"":" not", " factorion as ",
+        join("! + ", @digits), "! = ", join(" + ",@factorials),
+	" = $sum ", $factorion?"== ":"!= ", $_;
+}
+sub factorial {
+    my $n=shift;
+    return 1 if $n<=0;
+    return $n*factorial($n-1);
+}