@v=((grep { $_ <= $pivot } @$v), (grep { $_ > $pivot } @$v));

##</code><code>##

my @v=nkeysort { $_<$pivot ? $_ + 200 : $_ } @$v;

##</code><code>##

my @v=((sort {$a<=>$b} (grep { $_ >= $pivot } @$v)),
       (sort {$a<=>$b} (grep { $_ < $pivot } @$v)));

##</code><code>##

my @sorted = nkeysort {
  ( ( sort {$a<=>$b} (grep { $_ >= $pivot } @$_) ),
    ( sort {$a<=>$b} (grep { $_ <  $pivot } @$_) ) )[50]
} @data;