Sort takes O(n log n). Simply walking the keys of the hash is only O(n). 
my ($min, undef) = each %hash;
$min > $_ and $min = $_ for keys %hash;

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Updated: Fixed that bug...:)

In reply to Re: Returning the lowest key in a hash (or highest) by indigo
in thread Returning the lowest key in a hash (or highest) by deprecated

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