Re^2: Challenge: Twist On Bin Packing

japhy,
I am working on a brute force implementation so that people can test their theories. It isn't as easy as I thought it might have been.

Update: As pointed out by Anonymous Monk later in this thread with a bin size of 10 and an input list of 1,1,1,2,2,3,4,6,7,7 - this method fails

Cheers - L~R

Comment on Re^2: Challenge: Twist On Bin Packing

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Re^3: Challenge: Twist On Bin Packing
by japhy (Canon) on Apr 07, 2006 at 16:35 UTC

sub bin {
  my ($size, @set) = @_;
  my $best = [];
  my @bins;

  _bin($size, \@set, \@bins, 0, $best);
  print "BEST: <@{[ map qq{[@$_]}, @$best ]}>\n";
}


sub _bin {
  my ($size, $set, $bins, $i, $best) = @_;

  if (@$set == 0) {
    @$best = map [@$_], @$bins if @$bins > @$best;
    return;
  }

  my $rem = $size - sum($bins->[$i]);

  for (sort { $set->[$b] <=> $set->[$a] } grep { $set->[$_] <= $rem } 
+0 .. $#$set) {
    my $n = splice @$set, $_, 1;
    push @{ $bins->[$i] }, $n;
    _bin($size, $set, $bins, (sum($bins->[$i]) == $size) ? $i+1 : $i, 
+$best);
    _bin($size, $set, $bins, $i+1, $best) if 0 == grep { $set->[$_] <=
+ ($rem-$n) } 0 .. $#$set;
    pop @{ $bins->[$i] };
    pop @$bins if @{ $bins->[$i] } == 0;
    splice @$set, $_, 0, $n;
  }
}


sub sum {
  my $s = 0;
  $s += $_ for @{ $_[0] };
  $s;
}
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Jeff japhy Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and perl hacker
How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart

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