use strict;
use Algorithm::Combinatorics qw(variations);
use feature ':5.10'; 

my @operators = qw(+ - * /);
my @numbers = qw(9 -4 8 6 10);
my $total = 7; #required result

my $iter = variations(\@operators, 4); #get combinations for operators without rep. and loop
my $iter2 = variations(\@numbers, 5);  #get combinations for numbers without rep. and loop

while (my $p = $iter->next){
while (my $p2 = $iter2->next){

#escaping precedence
my $eval = eval ("$p2->[0] $p->[0] $p2->[1]");
$eval = eval ("$eval $p->[1] $p2->[2]");
$eval = eval ("$eval $p->[2] $p2->[3]");
$eval = eval ("$eval $p->[3] $p2->[4]");

if ($eval == $total){
say "$p2->[0] ($p->[0]) $p2->[1] ($p->[1]) $p2->[2] ($p->[2]) $p2->[3] ($p->[3]) $p2->[4] = 7"; }
}
$iter2 = variations(\@numbers, 5); #Resets the iterator
}