Solution to task 2

1 files changed, 68 insertions, 0 deletions

diff --git a/challenge-197/jo-37/perl/ch-2.pl b/challenge-197/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..413ed8d0b0
--- /dev/null
+++ b/challenge-197/jo-37/perl/ch-2.pl
@@ -0,0 +1,68 @@
+#!/usr/bin/perl -s
+
+use v5.16;
+use Test2::V0;
+use List::MoreUtils qw(zip part);
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+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 "@{[wiggle_sort(@ARGV)]}";
+
+
+### Implementation
+
+# Sort the list in descending order, split it in two and zip both parts.
+# For an odd sized list, the first part gets one more element.  "zip"
+# will then produce a trailing "undef" that will be omitted by the
+# slice.
+# If the list contains too many replicas of the same element then there
+# is no valid wiggle sorted list and the produced result will silently
+# violate the constraints.
+sub wiggle_sort {
+    my $i;
+    (&zip(
+        part {$i++ < $#_ / 2}
+        sort {$b <=> $a} @_
+    ))[0 .. $#_];
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+        is [wiggle_sort(qw(1 5 1 1 6 4))], [qw(1 6 1 5 1 4)], 'example 1';
+        is [wiggle_sort(qw(1 3 2 2 3 1))], [qw(2 3 1 3 1 2)], 'example 2';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+        is [wiggle_sort(qw(1 2 3 4 5))], [qw(3 5 2 4 1)], 'odd size';
+        is [(wiggle_sort(qw(1 1 1 1 1 2 3 4)))[6, 7]], [1, 1], '1 violates';
+        is [(wiggle_sort(qw(1 2 3 4 4 4 4)))[0, 1]], [4, 4], '4 violates';
+        is [wiggle_sort(-1, 0, 1)], [0, 1, -1], 'negative';
+	}
+
+    done_testing;
+    exit;
+}