slice by paragraph Perl的行截取

这样的字段，需要查询exon的在tran中间的exon次数，例如这里是2 3

kk@R61e:~$ cat test.txt
tran
exon
exon
tran
exon
exon
exon

use strict;
use warnings;
 
open FILE , "< /home/kk/test.txt" ;
chomp(my @string = <FILE>) ;
 
 
my %h ;
my $i = 0 ;
for ( @string ) {
    if (/tran/){
        $i++;
        next ;
    }
    $h{$i}++;
}
 
use Data::Dumper;
print Dumper(\%h);