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use Data::Dumper; ... my @array = qw (aa bb cc aa aa cc cc dd aa aa); %counts = map {$_ => ++$counts{$_} } @array; print Dumper(\%counts);
my %counts = map { my $n; do { $n = (($last=$_) ... ($last ne $_)) } while $n =~ /E0$/; ($last => $n); } sort @array;