and here's a version that uses recursion and allows duplicate q's:
use strict;
use warnings;
my @statements = qw(
~c->~f
g->b
p->f
c->~b
p->b
d->p
);
LHCC(parse(@statements));
sub LHCC {
my (%all) = @_;
my @arguments = sort {@$a <=> @$b} buildArguments(\%all, keys %all
+);
my $longest = @{$arguments[-1]};
@arguments = map {[join (' => ', @$_), $_->[0], $_->[-1]]}
grep {$longest == @$_} @arguments;
print " ", join "or ", map {"$_->[0]\n"} @arguments;
print "Syllogism(s)\n ", join "and ",
map {"$_->[1] => $_->[2]\n"} @arguments;
}
sub buildArguments {
my ($options, @keys) = @_;
my @arguments;
for my $key (@keys) {
next if !exists $options->{$key};
my @qKeys = @{$options->{$key}};
my $remaining = deepCopy($options, $key);
my @tails = buildArguments($remaining, @qKeys);
push @arguments, [$key, @$_] for @tails;
}
@arguments = map {[$_]} @keys if ! @arguments;
return @arguments;
}
sub deepCopy {
my ($part, @exclude) = @_;
my %copy;
if ('ARRAY' eq ref $part) {
return [map {deepCopy($_)} @$part];
} elsif ('HASH' eq ref $part) {
my %copy = map {$_ => deepCopy($part->{$_})} keys %$part;
delete $copy{$_} for @exclude;
return \%copy;
}
return $part;
}
sub parse {
my %all;
for my $statement (@_) {
my ($p, $q) = $statement =~ /(\S+)\s*->\s*(\S+)/;
push @{$all{$p}}, $q;
$_ = /^~(.*)/ ? $1 : "~$_" for $p, $q;
push @{$all{$q}}, $p;
}
return %all;
}
Prints:
d => p => f => c => ~b => ~p => ~d
or d => p => b => ~c => ~f => ~p => ~d
Syllogism(s)
d => ~d
and d => ~d
Note that this version has the statement data built in, but replacing @statements with @ARGV allows the command line parsing to be used instead of the test data.
I've switched to using ~ for negation instead of - too.
This version is a little more Perlish than the previous code. Use Perl documentation to look up functions and syntax you've not encountered before. You'll notice I've not bothered to suppress duplicate results - that's left as an exercise for the reader ;).
True laziness is hard work