@sorted_els = map  { $_->[0] }
              sort { $a->[1] <=> $b->[1] }
              map  { [$_, complex_calculation($_)] }
              @list;

##</code><code>##

# swapped $a/$b to get max
($max_el) = map  { $_->[0] }
            sort { $b->[1] <=> $a->[1] }
            map  { [$_, complex_calculation($_)] }
            @list;