use List::PowerSet qw/powerset_lazy/;
my @set = (0) x $N;
my @C   = (1) x 2**$N;
my $M = 0;
my $ps_itr = powerset_lazy(0 .. $N-1);
while (my $ref_set = $ps_itr->()) {
    $_ = 1 for local @set[@$ref_set];
    $C[ $M ] *= $arr->[ $_ ][ $set[$_] ] for 0 .. $N-1;
    $M++;
}