Solutions to challenge 190

2 files changed, 164 insertions, 0 deletions

diff --git a/challenge-190/jo-37/perl/ch-1.pl b/challenge-190/jo-37/perl/ch-1.pl
new file mode 100755
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+++ b/challenge-190/jo-37/perl/ch-1.pl
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+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0;
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [STR]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+STR
+    String to check for appropriate capital usage
+
+EOS
+
+
+### Input and Output
+
+say 0 + !!check_caps(shift);
+
+
+### Implementation
+
+# There is no need to restrict this task to ASCII letters.  For Unicode
+# characters there are properties "Letter uppercase" and "Letter
+# lowercase".  Using these here.
+sub check_caps {
+	shift =~ /^\p{Lu}?(?:\p{Lu}*|\p{Ll}*)$/;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        ok  check_caps('Perl'),   'Example 1';
+        ok  check_caps('TPF'),    'Example 2';
+        ok !check_caps('PyThon'), 'Example 3';
+        ok  check_caps('raku'),   'Example 4';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        ok  check_caps('Περλ'),   'Example 1 greek';
+        ok  check_caps('ΤΠΦ'),    'Example 2 greek';
+        ok !check_caps('ΠυΘων'),  'Example 3 greek';
+        ok  check_caps('ρακου'),  'Example 4 greek';
+        ok  check_caps('Π'),      'single uppercase';
+        ok  check_caps('ρ'),      'single lowercase';
+        ok !check_caps('1etter'), 'not a letter';
+
+	}
+
+    done_testing;
+    exit;
+}
diff --git a/challenge-190/jo-37/perl/ch-2.pl b/challenge-190/jo-37/perl/ch-2.pl
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index 0000000000..185ebd1406
--- /dev/null
+++ b/challenge-190/jo-37/perl/ch-2.pl
@@ -0,0 +1,97 @@
+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0;
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [CODE]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+CODE
+    code sequence
+
+EOS
+
+
+### Input and Output
+
+say for decode(shift);
+
+
+### Implementation
+
+# We have an encoding from letters starting with A, B, C, D to codes 1,
+# 2, 3, 4.  The end of the sequence is not specified by the task's
+# description, but from example 3 it becomes clear that the sequence
+# ends with Z.  Otherwise there would be a decoding for 27.
+#
+# A valid encoding thus must be matched by
+#   /^(?:[1-9]|1[0-9]|2[0-6])+$/
+# Capturing and recording the internal matches and forcing the regex
+# engine into backtracking reveals all possible partitions of the
+# encoding.
+
+sub decode {
+    my @part;
+    our @p;
+
+    # Split the encoding into all possible partitions:
+    shift =~ m{
+        ^
+        (?| ([1-9])  (?&REC)    # Process a matching branch, see below.
+          | (1[0-9]) (?&REC)
+          | (2[0-6]) (?&REC)
+        )+
+        $
+        (?{push @part, [@p]})   # Persist a complete partition.
+        (*FAIL)                 # Force backtracking.
+
+        (?(DEFINE)              # Define
+            (?<REC>             # a capture group named "REC" as:
+                (?{local @p = @p; push @p, $1})
+                                # Create a backtracking-safe copy of the
+                                # current (incomplete) partition and
+                                # record the previously captured part of
+                                # the string.
+            )
+        )
+    }x;
+
+    # Loop over the found partitions and convert the codes into their
+    # corresponding encoded ASCII characters.
+    map {pack 'C*', map ord('A') + $_ - 1, @$_} @part;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        is [decode(11)],   [qw(AA K)],                'Example 1';
+        is [decode(1115)], [qw(AAAE AAO AKE KAE KO)], 'Example 2';
+        is [decode(127)],  [qw(ABG LG)],              'Example 3';
+
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        is  decode(130),      F(),         'invalid zero';
+        is [decode(120)],     ['AT'],      'valid zero';
+        is [decode(3 x 128)], ['C' x 128], 'long code';
+	}
+
+    done_testing;
+    exit;
+}