Solution to task 2

1 files changed, 109 insertions, 0 deletions

diff --git a/challenge-318/jo-37/perl/ch-2.pl b/challenge-318/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..412b5cba32
--- /dev/null
+++ b/challenge-318/jo-37/perl/ch-2.pl
@@ -0,0 +1,109 @@
+#!/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 == 2;
+
+sub usage {
+    die <<~EOS;
+    $0 - reverse equals
+
+    usage: $0 [-examples] [-tests] [SOURCE TARGET]
+
+    -examples
+        run the examples from the challenge
+     
+    -tests
+        run some tests
+
+    SOURCE TARGET
+        two lists of integers
+
+    EOS
+}
+
+
+### Input and Output
+
+say +(qw(true false))[!reverse_equals(@ARGV)];
+
+
+### Implementation
+#
+# For details see:
+# https://github.sommrey.de/the-bears-den/2025/04/25/ch-318.html#task-2
+
+
+sub reverse_equals {
+    my ($s, $t) = map long($_), @_;
+    my $ne = which $s != $t;
+
+    $ne->isempty || all $s($ne(-1):$ne(0)) == $t($ne(0):$ne(-1));
+}
+
+
+### Examples and Tests
+
+sub run_tests ($examples, $tests) {
+    return unless $examples || $tests;
+
+    state sub run_example ($args, $expected, $name) {
+        my $result = reverse_equals(@$args);
+        is $result, $expected,
+            qq{$name: (@{[map "[@$_]", @$args]}) -> } . $expected->name;
+    }
+
+    plan 2;
+
+    $examples ? subtest_streamed(examples => sub {
+        my @examples = (
+            [[[3, 2, 1, 4], [1, 2, 3, 4]], T(), 'example 1'],
+            [[[1, 3, 4], [4, 1, 3]], F(), 'example 2'],
+            [[[2], [2]], T(), 'example 3'],
+        );
+        plan scalar @examples;
+        for (@examples) {
+            run_example @$_;
+        }
+    }) : pass 'skip examples';
+
+    $tests ? subtest_streamed(tests => sub {
+        plan 8;
+        ok  reverse_equals([2, 3, 5, 13, 11, 7, 17, 19],
+            [2, 3, 5, 7, 11, 13, 17, 19]), 'std';
+        ok  reverse_equals([13, 11, 7, 17, 19],
+            [7, 11, 13, 17, 19]), 'empty prefix';
+        ok  reverse_equals([2, 3, 5, 13, 11, 7],
+            [2, 3, 5, 7, 11, 13]), 'no suffix';
+        ok !reverse_equals([2, 3, 5, 11, 13, 7, 17, 19],
+            [2, 3, 5, 7, 11, 13, 17, 19]), 'not reverse';
+        ok  reverse_equals([13, 11, 7],
+            [7, 11, 13]), 'reverse odd';
+        ok  reverse_equals([17, 13, 11, 7],
+            [7, 11, 13, 17]), 'reverse even';
+        ok !reverse_equals([7, 11, 17],
+            [7, 13, 17]), 'different elements';
+        ok  reverse_equals([2, 3, 5, 7, 11, 13, 17, 19],
+            [2, 3, 5, 7, 11, 13, 17, 19]), 'equal';
+    }) : pass 'skip tests';
+
+    exit;
+}