$ cat qqq.txt
a
c

$ cat exp.txt
1       a
11      a
2       b
333     c

##</code><code>##

$ perl -Mstrict -Mwarnings -Mautodie=:all -E '
    use Tie::File;
    tie my @exp, q{Tie::File}, q{exp.txt};
    tie my @qqq, q{Tie::File}, q{qqq.txt};
    for my $search (@qqq) {
        my @results = map { $search eq $_->[1] ? $_->[0] : () }
                      map { [ split /\t/ ] } @exp;
        say "$search: @results";
    }
'
a: 1 11
c: 333