my $AoA = pack 'C*', map @$_, @AoA; my $omit = $AoA[0]; my $pat = '[^'.( join '', map quotemeta, pack 'C*', @$omit ).']{4}'; my $re = qr/\G(?:.{4})*?($pat)/s; my @matches = map [ unpack 'C*', $_ ], $AoA =~ /$re/g; #### my $AoA = pack '(C4S)*', map { @{ $AoA[$_] }, $_ } 0..$#AoA; my $omit = $AoA[0]; my $pat = '[^'.( join '', map quotemeta, pack 'C*', @$omit ).']{4}'; my $re = qr/\G(?:.{6})*?$pat(..)/s; my @matches = @AoA[ map unpack 'S', $AoA =~ /$re/g ];