>>316 Perl5

use Data::Dump 'dump';
sub fn {
　my ($le, $pv, @ri) = @_;
　defined $pv ? map {[$pv, @$_]} fn([], @$le, @ri) : ([])
　　,
　@ri ? fn([@$le, $pv], @ri) : ()
}
$N = 3;
@a = 1..$N;
print dump(fn [], @a);


実行結果
$ perl 18_308_N_permutation.pl
([1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2], [3, 2, 1])