{ # map columns to buckets. key is string, value is anonymous array. my %c2bMap; sub c2bMappings { my($buckets, $columns) = @_; die "bogus args" unless $buckets > 1 && $columns > $buckets; %c2bMap = (); _genFrom(0, (0) x ($columns - $buckets), 1 .. ($buckets - 1)); return \%c2bMap; } sub _genFrom { my @c2bMap = @_; return if exists $c2bMap{"@c2bMap"}; print "@c2bMap\n"; #DEBUG $c2bMap{"@c2bMap"} = \@c2bMap; foreach my $i ( 2 .. $#c2bMap ) { my $n = $c2bMap[$i] - 1; if ( $c2bMap[$i - 2] == $n && $c2bMap[$i - 1] == $n ) { local $c2bMap[$i-1] = $c2bMap[$i]; _genFrom(@c2bMap); } } } } c2bMappings(4,6); __END__ 0 0 0 1 2 3 0 0 1 1 2 3 0 1 1 1 2 3 0 1 1 2 2 3 0 1 2 2 2 3 0 1 2 2 3 3 0 1 2 3 3 3 0 1 1 2 3 3 0 0 1 2 2 3 0 0 1 2 3 3