Solution to task 1

1 files changed, 62 insertions, 0 deletions

diff --git a/challenge-249/jo-37/perl/ch-1.pl b/challenge-249/jo-37/perl/ch-1.pl
new file mode 100755
index 0000000000..df8c652043
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+++ b/challenge-249/jo-37/perl/ch-1.pl
@@ -0,0 +1,62 @@
+#!/usr/bin/perl -s
+
+use v5.24;
+use Test2::V0;
+
+our ($tests, $examples);
+
+run_tests() if $tests || $examples;	# does not return
+
+die <<EOS unless @ARGV;
+usage: $0 [-examples] [-tests] [N...]
+
+-examples
+    run the examples from the challenge
+ 
+-tests
+    run some tests
+
+N...
+    list of numbers
+
+EOS
+
+
+### Input and Output
+
+say join ", ", map "(@$_)", equal_pairs(@ARGV);
+
+
+### Implementation
+
+# Count the frequencies of all given numbers, check if these are all
+# even and build equal pairs.
+
+sub equal_pairs {
+	my %freq;
+    $freq{$_}++ for @_;
+    return () if grep $_ % 2, values %freq;
+
+    map +([$_, $_]) x ($freq{$_} / 2), keys %freq;
+}
+
+
+### Examples and tests
+
+sub run_tests {
+    SKIP: {
+        skip "examples" unless $examples;
+
+        is [equal_pairs(3, 2, 3, 2, 2, 2)],
+            bag {item [2, 2]; item [2, 2]; item [3, 3]; end;}, 'example 1';
+
+        is [equal_pairs(1, 2, 3, 4)], [] , 'example 2';
+    }
+
+    SKIP: {
+        skip "tests" unless $tests;
+	}
+
+    done_testing;
+    exit;
+}