#! perl
use strict;
use warnings;

my %HoA =
(
    no1  => [ 'c', 'd'      ],
    yes1 => [ 'X'           ],
    no2  => [ 'e', 'e', 'f' ],
    yes2 => [ 'a', 'X', 'b' ],
);

my $a = 'X';

for my $key (keys %HoA)
{
    print "Element '$a' found, key = $key\n" if grep {$_ eq $a} @{ $HoA{$key} };
}

##</code><code>##

13:00 >perl 1095_SoPW.pl
Element 'X' found, key = yes2
Element 'X' found, key = yes1

13:12 >