#!/usr/bin/env perl

use strict;
use warnings;
use List::MoreUtils(qw(uniq));

my @array = map {[split]} ("11 12", "11 13", "9 8 7", "3 4", "11 4");

my %g = ();

for my $i (@array) {
    my @v = map {@$_} uniq map {$g{$_} or [$_]} @$i;
    @g{@v} = (\@v) x @v;
}

print join ("\n", map {join " ", sort {$a<=>$b} @$_} uniq values %g), "\n";