Solutions to challenge 204

5 files changed, 136 insertions, 67 deletions

diff --git a/challenge-203/jo-37/ch-202.md b/challenge-203/jo-37/ch-202.md
deleted file mode 100644
index d9e5420ee0..0000000000
--- a/challenge-203/jo-37/ch-202.md
+++ /dev/null
@@ -1,33 +0,0 @@
-# Sequential adjacent consecutive second-next neighbors
-
-**Preface:**
-I wrote this text *after* I submitted my solution to the week 202's challenge *and* I looked throught  all other solutions that were submitted so far.
-
-I was surprised to see other interpretations of task 1 that I hadn't thought about. To restate:
-
-> Write a script to print 1 if there are THREE consecutive odds in the given array otherwise print 0.
-
-Sounds clear: three consecutive odds. But wait: What is the meaning of "consecutive"?
-I interpreted this as "three odd numbers consecutive in the list".  Another valid interpretation would be: "three consecutive odd numbers contained in the list".  Something completely different!
-
-An example for my interpretation:
-
-    2, 4, 9, 3, 7, 22
-has three consecutive odds: 9, 3, 7.
-
-On the other hand:
-
-    4, 9, 2, 11, 6, 7
-has three consecutive odds: 7, 9, 11.
-
-I refuse to interpret the task as: three consecutive consecutive odds, i.e.
-
-    2, 3, 5, 7, 8
-
-regarding as valid but refusing
-
-    7, 2, 5, 8, 3
-
-*and*
-
-    2, 7, 3, 5, 8
diff --git a/challenge-203/jo-37/perl/ch-2.pl b/challenge-203/jo-37/perl/ch-2.pl
index 2d6b9eadfb..b7ffe49a31 100755
--- a/challenge-203/jo-37/perl/ch-2.pl
+++ b/challenge-203/jo-37/perl/ch-2.pl
@@ -45,7 +45,6 @@ copy_dirs(@ARGV);
 sub copy_dirs ($source, $target) {
     find {
         # Make sure the source path is not interpreted as a regex.
-        # # Make sure the source path is not interpreted as a regex.
         wanted => sub {-d && s/^\Q$source\E/$target/ && !-e && mkdir},
         no_chdir => 1}, $source;
 }
diff --git a/challenge-204/jo-37/ch-202.md b/challenge-204/jo-37/ch-202.md
deleted file mode 100644
index d9e5420ee0..0000000000
--- a/challenge-204/jo-37/ch-202.md
+++ /dev/null
@@ -1,33 +0,0 @@
-# Sequential adjacent consecutive second-next neighbors
-
-**Preface:**
-I wrote this text *after* I submitted my solution to the week 202's challenge *and* I looked throught  all other solutions that were submitted so far.
-
-I was surprised to see other interpretations of task 1 that I hadn't thought about. To restate:
-
-> Write a script to print 1 if there are THREE consecutive odds in the given array otherwise print 0.
-
-Sounds clear: three consecutive odds. But wait: What is the meaning of "consecutive"?
-I interpreted this as "three odd numbers consecutive in the list".  Another valid interpretation would be: "three consecutive odd numbers contained in the list".  Something completely different!
-
-An example for my interpretation:
-
-    2, 4, 9, 3, 7, 22
-has three consecutive odds: 9, 3, 7.
-
-On the other hand:
-
-    4, 9, 2, 11, 6, 7
-has three consecutive odds: 7, 9, 11.
-
-I refuse to interpret the task as: three consecutive consecutive odds, i.e.
-
-    2, 3, 5, 7, 8
-
-regarding as valid but refusing
-
-    7, 2, 5, 8, 3
-
-*and*
-
-    2, 7, 3, 5, 8
diff --git a/challenge-204/jo-37/perl/ch-1.pl b/challenge-204/jo-37/perl/ch-1.pl
new file mode 100755
index 0000000000..6d9db6dac2
--- /dev/null
+++ b/challenge-204/jo-37/perl/ch-1.pl
@@ -0,0 +1,63 @@
+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0 '!float';
+use PDL;
+use PDL::NiceSlice;
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV > 1;
+usage: $0 [-examples] [-tests] [--] [N1 N2...]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+N1 N2...
+    List of numbers
+
+EOS
+
+
+### Input and Output
+
+say 0 + is_monotonic(@ARGV); 
+
+
+### Implementation
+
+# Comparing consecutive elements from the list yields values in the set
+# {-1, 0, 1}, where a non-monotonic list has both -1 and 1 in the result
+# set.  Summating over the absolute values of the unique results from
+# the comparisons thus reveals the monotonic property: The sum will be
+# two for a non-monotonic list. 
+sub is_monotonic {
+	my $list = pdl @_;
+
+    ($list(1:-1) <=> $list(0:-2))->uniq->abs->sum < 2;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        ok  is_monotonic(1, 2, 2, 3), 'example 1';
+        ok !is_monotonic(1, 3, 2),    'example 2';
+        ok  is_monotonic(6, 5, 5, 4), 'example 3';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+	}
+
+    done_testing;
+    exit;
+}
diff --git a/challenge-204/jo-37/perl/ch-2.pl b/challenge-204/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..8a550e738e
--- /dev/null
+++ b/challenge-204/jo-37/perl/ch-2.pl
@@ -0,0 +1,73 @@
+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0 '!float';
+use PDL;
+use experimental 'signatures';
+
+our ($tests, $examples, $rows, $cols);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV && $rows && $cols;
+usage: $0 [-examples] [-tests] [-rows=R -cols=C MATRIX]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+-rows=R
+-cols=C
+    reshape the given matrix to RxC
+
+MATRIX
+    a matrix in any string form accepted by the pdl constructor, e.g.
+    '[1 2] [3 4] [5 6]'
+
+EOS
+
+
+### Input and Output
+
+# Build an output string to be printed or use zero if it turns out to be
+# empty.
+say +(join "\n", map "[@$_]", @{reshape_matrix($rows, $cols, "@ARGV")}) || 0;
+
+
+### Implementation
+
+# PDL's "reshape" is too forgiving for this task: It pads or truncates
+# the data as needed.  Returning a reshaped matrix only when the number
+# of elements in both shapes match.
+sub reshape_matrix ($r, $c, @matrix) {
+	my $m = long @matrix;
+
+    $r * $c == nelem($m) ? $m->reshape($c, $r)->unpdl : [];
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        is reshape_matrix(1, 4, [1, 2], [3, 4]),
+            [[1, 2, 3, 4]], 'example 1';
+        is reshape_matrix(3, 2, [1, 2, 3], [4, 5, 6]),
+            [[1, 2], [3, 4], [5, 6]], 'example 2';
+        is reshape_matrix(3, 2, [1, 2]), [], 'example 3';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+
+        is reshape_matrix(3, 10, sequence(5, 6)), sequence(10, 3)->unpdl,
+            '6x5 -> 3x10';
+	}
+
+    done_testing;
+    exit;
+}