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; }