Kolakoski

Score: 58.20 (pass)

#!perl -l
s/.?/$ARGV[1&pos]x($&||1)/eg until/.{$ARGV[2]}/;print$&

Score: 59.23 (pass)

#!perl -l
$c=pop;s/.?/$ARGV[1&pos]x($&||1)/eg until/.{$c}/;print$&

Score: 64.25 (pass)

#!perl -l
print map{push@a,($y=$ARGV[~$_&1])x($a[0]||$y);shift@a}1..pop

Score: 70.27 (pass)

#!perl -l
*_=*ARGV;print map{push@a,($y=$_[~$_&1])x($a[0]||$y);shift@a}1..pop

Score: 72.26 (pass)

#!perl -l
*_=*ARGV;print map{push@a,($y=$_[~$_&1])x($a[--$_]||$y);$a[$_]}1..pop

Score: 77.26 (pass)

#!perl -l
*_=*ARGV;print map{push@a,($y=shift)x($a[--$_]||$y);$_[1]=$y;$a[$_]}1..pop

Score: 79.26 (pass)

#!perl -l
*_=*ARGV;print map{push@a,($y=shift)x($a[--$_]||$y);$_[1]=$y;$a[$_]}(1..pop)

Score: 86.28 (pass)

#!perl -l
*_=*ARGV;$c=pop;for(0..$c){push@a,($y=shift)x($a[$_]||$y);$_[1]=$y}print@a[0..$c-1]

Score: 88.28 (pass)

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

Score: 103.30 (pass)

First working attempt

#!perl -l
($x,$y,$c)=@ARGV;for(0..$c){push@a,($x)x($a[$_*2]||$x);push@a,($y)x($a[$_*2+1]||$y)}print@a[0..$c-1]