My interpretation of your question: Look at the keys of the hash in the order of the values of the hash and join the keys (as strings) with overlaps.

Under this assumption the steps are:

• Sort the keys by the values.
• Intialize your merged string with the first key.
• Determine the maximum overlap of the merged string with the next key. Start with the maximum overlapping length, use substr to retrieve the end of the merged string and the beginning of the next key and compare them. Reduce overlap until a match is found and append the rest to the merged string. If no match is found, just concatenate the two strings.
• Repeat with all keys.

How can I merge these to have janeen.

Are you asking a syntax question or an algorithm(steps) question?

Do you know which steps need to be taken, but just need the syntax to do it? What are these steps?

You can get an idea for the steps, and actual syntax needed by reading

Tutorials► Data Types and Variables ► Data Type: Array ► Data Type: Hash► References quick reference

More elaborate and coprehensive tutorial in http://learn.perl.org/books/beginning-perl/, Learn Perl in about 2 hours 30 minutes, perlintro, chromatics free book Modern Perl a loose description of how experienced and effective Perl 5 programmers work....You can learn this too.

If you have any questions feel free to ask but please be specific :)

What have you tried? See How (Not) To Ask A Question.

It seems you could naively use substr, perhaps like this (untested):

# rename %hash to %str2pos, as that seems an accurate name
my %str2pos = ( anee => '1', jane => '0', neen => '2', );
my $result;
for my $string(keys %str2pos) {
    substr($result,$str2pos{$string},length($string),$string);
}
print "$result\n";
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Instead of substr you could also use regular expressions. Concatenate all your strings in the correct order with a delimiter character that is not part of the strings, eg. #. Then find the same sequence of characters to the left and right of each delimiter and remove one side. It could look like this:

my %hash = ( anee => '1', jane => '0', neen => '2', ); 
my $merge = join '#', sort { $hash{$a} <=> $hash{$b} } keys %hash;
$merge =~ s/([^#]*)#(?=\1)//g;
print "$merge\n";
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Interesting homework question. Hint: sort on values.

Wait... what? hdb's answer was exactly what you needed? Don't get me wrong, it's clever and there's a good chance it's fast, but anybody reading your code will have no idea what the hell is going on. I have to agree with some of the other posters that some kind of sort with substring is the right way to go here. Even if it's slower, at least it properly conveys your intent.

shrug...   You can’t hope for any sort of meaningful answer until you make it clear what you want to do.   I only see three keys here, each with different values.   No rule by which to piece them together.   No idea what sort of rule you would consider “correct.”   Not even a guess.