1 files changed, 102 insertions, 0 deletions
diff --git a/challenge-337/jo-37/perl/ch-1.pl b/challenge-337/jo-37/perl/ch-1.pl
new file mode 100755
index 0000000000..88b3897405
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+++ b/challenge-337/jo-37/perl/ch-1.pl
@@ -0,0 +1,102 @@
+#!/usr/bin/perl
+
+use v5.26;
+use Test2::V0 qw(!float -no_srand);
+use Test2::Tools::Subtest 'subtest_streamed';
+use Getopt::Long;
+use experimental 'signatures';
+
+use PDL;
+use PDL::NiceSlice;
+
+### 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 - smaller than current
+
+    usage: $0 [-examples] [-tests] [--] [N]
+
+    -examples
+        run the examples from the challenge
+     
+    -tests
+        run some tests
+
+    N...
+        list of numbers
+
+    EOS
+}
+
+
+### Input and Output
+
+say smaller_than_current(@ARGV);
+
+
+### Implementation
+#
+# For details see:
+# https://github.sommrey.de/the-bears-den/2025/09/05/ch-337.html#task-1
+
+
+sub smaller_than_current {
+    my $num = pdl @_;
+    my $sort = $num($num->qsorti);
+    $sort .= $sort(-1:0)->dummy(0)->enumvec->(-1:0);
+    $sort += sequence $num;
+    $num;
+}
+
+
+### Examples and Tests
+
+sub run_tests ($examples, $tests) {
+    return unless $examples || $tests;
+
+    state sub run_example ($args, $expected, $name) {
+        my $result = smaller_than_current(@$args)->unpdl;
+        is $result, $expected,
+            "$name: (@$args) -> (@$expected)";
+    }
+
+    plan 2;
+
+    $examples ? subtest_streamed(examples => sub {
+        my @examples = (
+            [[6, 5, 4, 8], [2, 1, 0, 3], 'example 1'],
+            [[7, 7, 7, 7], [3, 3, 3, 3], 'example 2'],
+            [[5, 4, 3, 2, 1], [4, 3, 2, 1, 0], 'example 3'],
+            [[-1, 0, 3, -2, 1], [1, 2, 4, 0, 3], 'example 4'],
+            [[0, 1, 1, 2, 0], [1, 3, 3, 4, 1], 'example 5'],
+        );
+        plan scalar @examples;
+        for (@examples) {
+            run_example @$_;
+        }
+    }) : pass 'skip examples';
+
+    $tests ? subtest_streamed(tests => sub {
+        my @tests = (
+            [[4,1,3,1,4,1,3,1,3,1], [9,4,7,4,9,4,7,4,7,4], 'repeated values'],
+        );
+        plan scalar @tests;
+        for (@tests) {
+            run_example @$_;
+        }
+    }) : pass 'skip tests';
+
+    exit;
+}