Have you reviewed your course material? I would expect that it covers everything you need to approach this problem.

Please help us give you better answers. Show us what code you have already written, and explain to us what it does and where it fails to do what you need.

Also review push, split and likely perlsyn.

I tried alot.

Why not provide a couple of the algorithms which you tried? Someone might then be able to point out where you were going wrong. Perhaps even one of those algorithms was a valid one and it was merely your code which was flawed. But again, with neither algorithm nor code to view we will never know.

The key to this kind of problem is that when the line begins with a "continue-command"(plus) you want to process the rest of the line using the last "state" you were in, but when it doesnt begin with a "continue-command"(plus) you want to capture the new state, process the rest of the line with the new state, and remember that new state as the last_state for any following "continue-command"(plus) lines. Something like this

my $last_state=''; 

  while (my $line= <DATA>) { 
    chomp $line; 
    next unless ($line); 
    if (substr($line,0,1) eq '+') {
      # if line starts with a plus use last_state to process 
      process($last_state,substr($line,1));
      } 
    else { 
      # otherwise set last_state and process with it
      my @parts=split(' ',$line,2); 
      $last_state=$parts[0]; 
      process($last_state,$parts[1]);
      } 
  
    } # line 
sub process { 
  my $state=shift; 
  my $input=shift; 
  ... do stuff based on $state and $input ... 
  } # process
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