###
### partition-it
###

## Chapter 5 section 1.1

sub make_partitioner {
  my ($n, $treasures) = @_;
  my @todo = [$n, $treasures, []];
  sub { 
    while (@todo) {
      my $cur = pop @todo;
      my ($target, $pool, $share) = @$cur;
      if ($target == 0) { return $share }
      next if $target < 0 || @$pool == 0;
      my ($first, @rest) = @$pool;        
      push @todo, [$target-$first, \@rest, [@$share, $first]],
                  [$target       , \@rest,   $share         ];
    }
    return undef;
  } # end of anonymous iterator function       
} # end of make_partitioner