Topological Sort

Score: 145.44 (pass)

#!perl -l -0
($s=$\.<>)=~s/^(\S+) \1$/\1/gm;$s=~s/(\s)\Q$t[0]\E(?=\s)/$1/gm&&print$t[0]while@t=grep$s!~/\S \Q$_\E$/m,$s=~/^ *(\S+)(?:\s)/gm;exit$s=~/\S/

Score: 147.44 (pass)

#!perl -l -0
($s=$\.<>)=~s/^(\S+) \1$/\1/gm;while(@t=grep$s!~/\S \Q$_\E$/m,$s=~/^ *(\S+)(?:\s)/gm){$s=~s/(\s)\Q$t[0]\E(?=\s)/$1/gm;print$t[0]}exit$s=~/\S/