...
     @paths = sort { @$a <=> @$b } @paths;
my   @sets;
push @sets, set(@$_) for @paths;
my   @filtered;
...

##</code><code>##

16:12 >perl 1681_SoPW.pl
(Q R V)
(C D V)
(N P Q)
(E T V X)
(E N O P)
(I N T U Z)
(B D R W Z)
(A N O X Z)
(B L O R T)
(D H S X Y)
(D F J K O P T)
(D J M R S T V)
(B H J L N P U)
(A B H P R V X)
(C F L M T Y)
(C I J L M O X Y)
(D H I P S T V Y)
(A B D F G O U W)
(A C D E H J L N S Z)
(D F G M O S U W Y)
(A C G H J K P V Z)
(E H K M N P T V)
(F H I L O T V Z)

16:12 >

##</code><code>##

...
my   @sets;
push @sets, set(@$_) for @paths;
     @sets = sort { $a->size <=> $b->size } @sets;
my   @filtered;
...

##</code><code>##

17:06 >perl 1681_SoPW.pl
(Q R V)
(C D V)
(N P Q)
(E N O P)
(E T V X)
(D H S X Y)
(I N T U Z)
(B D R W Z)
(A N O X Z)
(B L O R T)
(C F L M T Y)
(B H J L N P U)
(A B H P R V X)
(D F J K O P T)
(D J M R S T V)
(E H K M N P T V)
(F H I L O T V Z)
(D H I P S T V Y)
(A B D F G O U W)
(C I J L M O X Y)
(D F G M O S U W Y)
(A C G H J K P V Z)
(A C D E H J L N S Z)

17:08 >