This is a faster way to count unique characters, using /s (Squash duplicate replaced characters) option of "tr":

$_ = "abcdeaacde"; 
$_=join ("",sort split //); 
tr/a-z//s; 
print length;

[download]

output: 5

In reply to Re: Coffee time quiz by fglock
in thread Coffee time quiz by perlmoth

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