#! perl -slw
use strict;
use Data::Dump qw[ pp ];

my @array = ("11 12","11 13", "9 8 7", "3 4", "11 4 111") ;

## combine
AGAIN: for my $i ( 0 .. $#array ) {
	for my $j ( $i+1 .. $#array ) {
		for my $n (split ' ', $array[ $j ]){
			if( $array[ $i ] =~ m[\b$n\b] ) {
				$array[ $i ] .= ' ' . splice @array, $j, 1;
				redo AGAIN;
			}
		}
	}
}
## dedup
for ( @array ) {
	1 while s[(\b\d+)\s(?=.*\b\1\b)][]g;
}

pp \@array;