Solution to task 2

1 files changed, 100 insertions, 0 deletions

diff --git a/challenge-332/jo-37/perl/ch-2.pl b/challenge-332/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..b3f0c6b957
--- /dev/null
+++ b/challenge-332/jo-37/perl/ch-2.pl
@@ -0,0 +1,100 @@
+#!/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 == 1;
+
+sub usage {
+    die <<~EOS;
+    $0 - odd letters
+
+    usage: $0 [-examples] [-tests] [STR]
+
+    -examples
+        run the examples from the challenge
+     
+    -tests
+        run some tests
+
+    STR
+        a string
+
+    EOS
+}
+
+
+### Input and Output
+
+say +(qw(true false))[!odd_letters(shift)];
+
+
+### Implementation
+#
+# For details see:
+# https://github.sommrey.de/the-bears-den/2025/08/01/ch-332.html#task-2
+
+sub odd_letters {
+    shift !~ /
+    (.)
+    (?!(?=(.*))(\1.+(?=\g{-2}$)|(?<=(?=x^|(?-1)).)))
+    ((??{qr([^$1]*)})\1)
+    (?:(?-1){2})*
+    (?!.*\1)
+    /x;
+}
+
+
+### Examples and Tests
+
+sub run_tests ($examples, $tests) {
+    return unless $examples || $tests;
+
+    state sub run_example ($args, $expected, $name) {
+        my $result = odd_letters(@$args);
+        is $result, $expected,
+            "$name: (@$args) -> " . $expected->name;
+    }
+
+    plan 2;
+
+    $examples ? subtest_streamed(examples => sub {
+        my @examples = (
+            [["weekly"], F(), 'example 1'],
+            [["perl"], T(), 'example 2'],
+            [["challenge"], F(), 'example 3'],
+        );
+        plan scalar @examples;
+        for (@examples) {
+            run_example @$_;
+        }
+    }) : pass 'skip examples';
+
+    $tests ? subtest_streamed(tests => sub {
+        my @tests = (
+            [["abccbabac"], T(), 'all multiple'],
+            [["abccbababc"], F(), 'all multiple, single even'],
+        );
+        plan scalar @tests;
+        for (@tests) {
+            run_example @$_;
+        }
+    }) : pass 'skip tests';
+
+    exit;
+}