perl -E "say for grep{eval $_ == 100} glob join '{+,-,}',1..9"


##</code><code>##


 perl -E "say for grep{eval $_ == 100} glob '{-,}'.join '{+,-,}',1..9"


##</code><code>##

perl -MList::Util="first" -E "@c[0..10**6]=(0..10**6);say for grep{$e=eval;$c[$e]=undef if $e>=0;$h{$e}++;eval $_==100}glob'{-,}'.join'{+,-,}',1..9;END{say for(sort{$h{$b}<=>$h{$a}}grep{$_>=0}keys %h)[0],first{defined $_}@c;say for(sort{$b<=>$a}grep{$_>0}keys %h)[0..9]}"

-1+2-3+4+5+6+78+9
1+2+3-4+5+6+78+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+67-89
123+45-67+8-9
123-4-5-6-7+8-9
123-45-67+89
9
211
123456789
23456790
23456788
12345687
12345669
3456801
3456792
3456790
3456788
3456786