Postorder

Score: 63.12 (pass)

#!perl -l
$_=pop;for$a(pop=~/./g){s/^(.*)$a(.*)$/$1
$2
$a/gm}print/./g

Score: 65.10 (pass)

#!perl -l
$_=pop;for$a(pop=~/./g){s/^(.*)$a(.*)$/$1\n$2\n$a/gm}print/./g

Score: 69.10 (pass)

#!perl -l
$_=pop;for$a(pop=~/./g){s/^(.*)$a(.*)$/$1\n$2\n$a/gm}s/\n//g;print

Score: 73.15 (pass)

#!perl -l
$_=" $ARGV[0] ";for$a(pop=~/./g){s/( .*)$a(.*? )/$1 $2$a/}s/ //g;print

Score: 74.09 (pass)

#!perl
sub P{pop=~/./;my$x=$&;map$_&&P($_,$'),split$x,pop;print$x}P@ARGV;print"
"

Score: 75.08 (pass)

#!perl
sub P{pop=~/./;my$x=$&;map$_&&P($_,$'),split$x,pop;print$x}P@ARGV;print"\n"

Score: 87.09 (pass)

#!perl
sub P{$_[0]=~s/(.)//;my$x=$1;map{$_&&P($_[0],$_)}split$x,$_[1];print$x}P@ARGV;print"\n"