Kolakoski

Score: 73.27 (pass)

#!perl -l
$l=pop;@l=(@l,($m=$ARGV[$|--])x($l[$_]||$m))for 0..$l;print@l[0..$l-1]

Score: 82.27 (pass)

#!perl -l
($x,$y,$l)=@ARGV;@l=(@l,($m=--$|?$x:$y)x($l[$_]||$m))for 0..$l;print@l[0..$l-1]

Score: 90.28 (pass)

#!perl -l
($x,$y,$l)=@ARGV;push@l,($x)x($l[$c++]||$x)and($x,$y)=($y,$x)for 1..$l;print@l[0..$l-1]