my $code = join "\n;\n", map {sprintf '$count{ $_ } = tr/%s/%s/', $_, $_ } @alphabet;
my %count;
local $_ = $string1;
eval $code;

##</code><code>##

my $code2 = join "\n+\n", map {sprintf 'abs($count{ %s } - tr/%s/%s/)', $_, $_, $_ } @alphabet;
local $_ = $string2;
eval $code2;