perl 获取文件内容里第一个AAA和最后一个AAA

<pre name="code" class="html">[root@wx03 ~]# cat -n aaa
     1	3`13
     2	edqae
     3	daa
     4	313
     5	1313
     6	1
     7	AAAhash1
     8	e31
     9	dad
    10	fad
    11	AAAA
    12	32131
    13	AAA
    14	qe
    15	dad
    16	AAA
    17	fdaaf
    18	fafa
    19	AAAhash2
[root@wx03 ~]# cat q1.pl
my @arr=();
open (LOG ,"<","aaa");
      while (<LOG>) {
      if ($_ =~/AAA/){$num=$.;push (@arr,$num); $hash{$num}=$_;};
};
print $arr[0]."\n";
print $hash{$arr[0]}."\n";
print $arr[-1]."\n";
print $hash{$arr[-1]}."\n";

[root@wx03 ~]# perl q1.pl
7
AAAhash1

19
AAAhash2