For summing to 100, I got all but one with this

#!/usr/bin/env perl
use strict;
use warnings;
use feature 'say';

my @queue = '123456789';

while (@queue) {
        $_ = shift @queue;
        say if eval == 100;
        while ( /\d+?/g) {
                next if (!$' || $' =~ /\+|\-/);
                push @queue,("$`$&+$'","$`$&-$'");
        }
}
[download]

123-45-67+89
123+4-5+67-89
123+45-67+8-9
1+2+34-5+67-8+9
1+23-4+5+6+78-9
1+23-4+56+7+8+9
12+3+4+5-6-7+89
12+3-4+5+67+8+9
12-3-4+5-6+7+89
123-4-5-6-7+8-9
1+2+3-4+5+6+78+9
[download]

Eventually resorted to this to get the last one

#!/usr/bin/env perl
use strict;
use warnings;
use feature 'say';

my @queue = '123456789';

my %seen;

while (@queue) {
    local $_ = shift @queue;
    next if (exists $seen{$_});
    $seen{$_}++;
    say if eval == 100;
    while (/\d+?/g) {
        my ($pre,$match,$post) = ($`,$&,$');
        push @queue, "$pre$match+$post" unless (!$post || $post =~ /[+
+-]/);
        push @queue, "$pre-$match$post" unless ($pre =~ /[-+]$/ );
    }
}
[download]

I think a better regex solution exists, this re-evaluates too many times. I used structure from tybalt89's Re: Parks Puzzle.

With '1234567891234' 1222 solutions

• choroba 13.459s
• Discipulus 19.835s
• tripledubs 38.762s

With '12345678912345' 3080 solutions

• choroba 42.444s
• Discipulus 1m 30s
• tripledubs 2m 4s