Data commit

Task/Combinations/Perl5i/combinations.p5i

@@ -0,0 +1,22 @@
+use perl5i::2;
+
+# ----------------------------------------
+# generate combinations of length $n consisting of characters
+# from the sorted set @set, using each character once in a
+# combination, with sorted strings in sorted order.
+#
+# Returns a list of array references, each containing one combination.
+#
+func combine($n, @set) {
+  return unless @set;
+  return map { [ $_ ] } @set if $n == 1;
+
+  my ($head) = shift @set;
+  my @result = combine( $n-1, @set );
+  for my $subarray ( @result ) {
+   $subarray->unshift( $head );
+  }
+  return ( @result, combine( $n, @set ) );
+}
+
+say @$_ for combine( 3, ('a'..'e') );