Solve PWC 285

3 files changed, 45 insertions, 0 deletions

diff --git a/challenge-285/wlmb/blog.txt b/challenge-285/wlmb/blog.txt
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+https://wlmb.github.io/2024/09/02/PWC285/
diff --git a/challenge-285/wlmb/perl/ch-1.pl b/challenge-285/wlmb/perl/ch-1.pl
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+++ b/challenge-285/wlmb/perl/ch-1.pl
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+#!/usr/bin/env perl
+# Perl weekly challenge 285
+# Task 1:  No Connection
+#
+# See https://wlmb.github.io/2024/09/02/PWC285/#task-1-no-connection
+use v5.36;
+use experimental qw(for_list);
+die <<~"FIN" unless @ARGV and @ARGV%2==0;
+    Usage: $0 I1 O1 I2 O2...
+    where Ii is the incoming and Oi the outgoing node
+    of the i-th edge.
+    FIN
+my (%in, %out);
+for my($in,$out)(@ARGV){
+    ++$in{$in} if $in ne $out;
+    ++$out{$out};
+}
+say "@ARGV -> ", join " ", grep{!$in{$_}}keys %out;
diff --git a/challenge-285/wlmb/perl/ch-2.pl b/challenge-285/wlmb/perl/ch-2.pl
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+#!/usr/bin/env perl
+# Perl weekly challenge 285
+# Task 2:  Making Change
+#
+# See https://wlmb.github.io/2024/09/02/PWC285/#task-2-making-change
+use v5.36;
+use Memoize;
+die <<~"FIN" unless @ARGV;
+    Usage: $0 A1 A2...
+    to find in how many ways can the amounts Ai can be
+    formed with coins (pennies, nickels, dimes, quartes
+    and half-dollars)
+    FIN
+memoize qw(number_of_ways);
+my @values=(1,5,10,25,50); # sorted
+my $large=1+$values[-1]; # larger than largest coin
+for(@ARGV){
+    say "$_ -> ",number_of_ways($_+$large, $large)
+}
+sub number_of_ways($amount,$first_coin){
+    return 0 if $first_coin>$amount;
+    return 1 if $first_coin==$amount;
+    my $total;
+    $total+=number_of_ways($amount-$first_coin, $_)for grep{$_<=$first_coin}@values;
+    return $total;
+}