use strict;
my $n = shift @ARGV;
my $try = [ $n ];
while ($try) {
print join(' ', @$try), "\n";
$try = next_partition($try);
}
exit 0; # all done
sub next_partition {
my $current = shift; # an arrayref of numbers in descending order
# find the last entry greater than one
my $i;
for ($i = 0; $i < @$current; ++$i) {
last if $current->[$i] == 1;
}
--$i;
# if all ones, there is no next partition
return undef if $i < 0;
# we'll strip off all the ones, and one more
my $count = @$current - $i;
# and must generate the first partition of that count
# subject to a top limit of what's to our left
my $limit = --$current->[$i];
# replace the ones
splice @$current, $i + 1, $count - 1,
# with the first paritition (limited) of the count
($limit) x int($count / $limit), grep $_, $count % $limit;
$current;
}