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-rwxr-xr-xchallenge-249/jo-37/perl/ch-1.pl62
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;
+}