my @lines = ("AB","ACFI","ADGJ","AE","BCDE","BFHJ","BI","EGHI","EJ","I
+J");

foreach my $i ("A".."H") {
        foreach my $j (++(my $ii = $i) .. "I") {
                foreach my $k (++(my $jj = $j) .. "J") {
                        print "$i$j$k\n" if 3 == grep {/$i.*$j|$i.*$k|
+$j.*$k/} @lines;                          
                }
        }
}
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