sub path { (*g,$f,$t)=@_;@s=map[$f,$_,$r{$_}],keys%{*r=$g{$f}}; push@s,map[@p,$_,$d+$r{$_}],keys%{*r=$g{$n}} while(@s=sort{$b->[-1]<=>$a->[-1]}@s),$d=pop@{*p=pop@s}, ($n=$p[-1])ne$t;@p }