Even if you didn't know how to use "x" to do what you want, it's not messy to do it without "x".

# With "x"
for my $i (0..$#count) {
    push @result, ($i) x $count[$i];
}
[download]

# Without "x"
for my $i (0..$#count) {
    for (1..$count[$i]) {
        push @result, $i;
    }
}
[download]