Solve PWC 156

3 files changed, 47 insertions, 0 deletions

diff --git a/challenge-156/wlmb/blog.txt b/challenge-156/wlmb/blog.txt
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+https://wlmb.github.io/2022/03/14/PWC156/
diff --git a/challenge-156/wlmb/perl/ch-1.pl b/challenge-156/wlmb/perl/ch-1.pl
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+#!/usr/bin/env perl
+# Perl weekly challenge 156
+# Task 1: Pernicious numbers
+#
+# See https://wlmb.github.io/2022/03/14/PWC156/#task-1-pernicious-numbers
+use v5.12;
+use warnings;
+use bigint;
+use Math::Prime::Util qw(is_prime);
+use List::Util qw(sum0);
+my $N=shift//10; # How many pernicious numbers to calculate
+my $candidate=0;
+my @pernicious;
+for(1..$N){
+    push(@pernicious, $candidate), next
+        if is_prime(sum0 split "", sprintf "%b", ++$candidate);
+    redo
+}
+say "The first $N pernicious numbers are ", join ", ",  @pernicious;
diff --git a/challenge-156/wlmb/perl/ch-2.pl b/challenge-156/wlmb/perl/ch-2.pl
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+#!/usr/bin/env perl
+# Perl weekly challenge 156
+# Task 2: Weird number
+#
+# See https://wlmb.github.io/2022/03/14/PWC156/#task-2-weird-number
+use v5.12;
+use warnings;
+use Math::Prime::Util qw(divisors);
+use Algorithm::Combinatorics qw(subsets);
+use List::Util qw(sum0);
+die "Usage: ./ch-2.pl N1 N2... to test numbers N1, N2... for weirdness"
+    unless @ARGV;
+my $is_weird;
+ WEIRD:
+    for my $N(@ARGV){
+        say("Arguments must be larger than 1"), next unless $N>=2;
+        my @divisors=divisors($N);
+        pop @divisors; # keep only proper divisors
+        $is_weird=0, next WEIRD unless sum0(@divisors)>$N; # Overabundant?
+        my @subsets=subsets(\@divisors);
+        for(@subsets){
+            $is_weird=0, next WEIRD if sum0(@$_)==$N; #Semiperfect, fail
+        }
+        $is_weird=1;
+} continue {
+    say "$N ", $is_weird?"is":"is not", " weird";
+}