Solution to task 2

1 files changed, 130 insertions, 0 deletions

diff --git a/challenge-336/jo-37/perl/ch-2.pl b/challenge-336/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..136d2bad93
--- /dev/null
+++ b/challenge-336/jo-37/perl/ch-2.pl
@@ -0,0 +1,130 @@
+#!/usr/bin/perl
+
+use v5.26;
+use Test2::V0 -no_srand;
+use Test2::Tools::Subtest 'subtest_streamed';
+use Getopt::Long;
+use experimental 'signatures';
+
+
+### Options and Arguments
+
+my ($tests, $examples, $verbose);
+GetOptions(
+    'examples!' => \$examples,
+    'tests!'    => \$tests,
+    'verbose!'  => \$verbose,
+) or usage();
+
+run_tests($examples, $tests);	# tests do not return
+
+usage() unless @ARGV;
+
+sub usage {
+    die <<~EOS;
+    $0 - final score
+
+    usage: $0 [-examples] [-tests] [-- S...]
+
+    -examples
+        run the examples from the challenge
+     
+    -tests
+        run some tests
+
+    S...
+        list of scores
+
+    EOS
+}
+
+
+### Input and Output
+
+say final_score(@ARGV);
+
+
+### Implementation
+#
+# For details see:
+# https://github.sommrey.de/the-bears-den/2025/08/29/ch-336.html#task-1
+
+package Score;
+
+sub new ($class) {
+    bless [], $class;
+}
+
+sub total ($self) {
+    List::Util::sum0 @$self;
+}
+
+sub apply ($self, @scores) {
+    for (@scores) {
+        push(@$self, $_), next if /^[-+]?\d+$/;
+        pop(@$self), next if /^C$/;
+        push(@$self, 2 * ($self->[-1] // 0)), next if /^D$/;
+        push(@$self, ($self->[-2] // 0) + ($self->[-1] // 0)), next if /^\+$/;
+        die "score invalid: $_";
+    }
+    $self;
+}
+
+
+package main;
+
+sub final_score {
+    Score->new->apply(@_)->total;
+}
+
+
+### Examples and Tests
+
+sub run_tests ($examples, $tests) {
+    return unless $examples || $tests;
+
+    state sub run_example ($args, $expected, $name) {
+        my $result = final_score(@$args);
+        is $result, $expected,
+            "$name: (@$args) -> $expected";
+    }
+
+    plan 2;
+
+    $examples ? subtest_streamed(examples => sub {
+        my @examples = (
+            [["5","2","C","D","+"], 30, 'example 1'],
+            [["5","-2","4","C","D","9","+","+"], 27, 'example 2'],
+            [["7","D","D","C","+","3"], 45, 'example 3'],
+            [["-5","-10","+","D","C","+"], -55, 'example 4'],
+            [["3","6","+","D","C","8","+","D","-2","C","+"], 128, 'example 5'],
+        );
+        plan scalar @examples;
+        for (@examples) {
+            run_example @$_;
+        }
+    }) : pass 'skip examples';
+
+    $tests ? subtest_streamed(tests => sub {
+        plan 9;
+        
+        like dies {Score->new->apply('X')}, qr/score invalid/,
+            'score invalid';
+        is(Score->new->total, 0, 'empty stack');
+        is(Score->new->apply('+')->total, 0, 'zero summands');
+        is(Score->new->apply('1')->apply('+')->total, 2, 'one summand');
+        is(Score->new->apply('D')->total, 0, 'double nothing');
+        is(Score->new->apply('C')->total, 0, 'cancel on empty stack');
+        {
+            my $x = Score->new;
+            $x->apply(3);
+            $x->apply(2);
+            $x->apply('+');
+            is $x->total, 10, 'single scores';
+        }
+        is(Score->new->apply(3)->apply(2)->apply('+')->total, 10, 'chained');
+        is(Score->new->apply(qw(3 2 +))->total, 10, 'multiple scores');
+    }) : pass 'skip tests';
+
+    exit;
+}