sub nn_single {
    @_=sort{$a<=>$b}@_;
    $_{abs$_[$_]-$_[$_-1]}=[$_-1,$_]for 1..$#_;
    @_[@{$_{(sort{$a<=>$b}keys%_)[0]}}]
}

##</code><code>##

sub nn_dup {
    my$s=sub{sort{$a<=>$b}keys%_};
    @_{@_}=0;
    @_=&$s;
    %_=();
    $_{abs$_[$_]-$_[$_-1]}=[$_-1,$_]for 1..$#_;
    @_[@{$_{(&$s)[0]}}]
}