Solution to task 2

1 files changed, 56 insertions, 0 deletions

diff --git a/challenge-247/jo-37/perl/ch-2.pl b/challenge-247/jo-37/perl/ch-2.pl
new file mode 100755
index 0000000000..852871a4d2
--- /dev/null
+++ b/challenge-247/jo-37/perl/ch-2.pl
@@ -0,0 +1,56 @@
+#!/usr/bin/perl -s
+
+use v5.24;
+use Test2::V0 '!float';
+use PDL;
+use PDL::Char;
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV == 1;
+usage: $0 [-examples] [-tests] [S]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+S
+    string of lower case ascii characters
+
+EOS
+
+
+### Input and Output
+
+say most_frequent_pair(shift);
+
+
+### Implementation
+
+sub most_frequent_pair {
+	my $s = PDL::Char->new(shift);
+    my ($count, $pairs) = rlevec($s->lags(0, 1, $s->dim(0) - 1)->qsortvec);
+    $pairs->atstr($count->long->maximum_ind);
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+        is most_frequent_pair('abcdbca'), 'bc', 'example 1';
+        is most_frequent_pair('cdeabeabfcdfabgcd'), 'ab', 'example 2';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+	}
+
+    done_testing;
+    exit;
+}