If the only thing about the order of your permutations that matters, is keeping the number of 0's as low as possible for as long as possible, then another way to accomplish your goal would be to create a complete set of permutations in any order, and then sort the set of permutations according to the number of 0's in each.

For example (using @a...@e):

for my $a (0..@a) {
  for my $b (0..@b) {
    for my $c (0..@c) {
      for my $d (0..@d) {
        for my $e (0..@e) {
# Build a hash with the permutation as the key, and the
# number of zeros as the value
  $permutation{$a[$a].$b[$b].$c[$c].$d[$d].$e[$e]} =
    !$a + !$b + !$c + !$d + !$e;
}}}}}

# Now sort according to the number of zeros
return sort {$permutation{$a} <=> $permutation{$b}} keys %permutation;
[download]

If you want more order than just "least number of zeros first," then you can create a more complex sorting routine using an || operator to break the tie between equal numbers of zeros. For example, to sort first according to number of zeros, and then asciibetical on the permutation created, use this:

return sort {$permutation{$a} <=> $permutation{$b} ||
             $a cmp $b} keys %permutation;
[download]

This code doesn't treat @c any differently than the rest of the arrays. If you don't care about @c, you could simply leave it out of the "number of zeros" calculation when assigning things into %permutation.

I hope this helps.

Goshdarnit they both beat me to it, and with nearly the same answer... :)

Alan

---

---

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:

  <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>

• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or How to display code and escape characters are good places to start.