In my previous question in this thread I asked to count the number of occurrences of all permutations with repetitions. What if I only wanted to not have the count but a binary answer (i.e. 0 or 1) if a specific permutation is in my string? There must be a way to just change the regexp in a minor way.

Up until now I used the suggested solution of:

$n=4;
$str="abababbcad";
%count;
while($str =~ m[(?=([abcd]{$n})).]g){
                   ++$count{ $1};     
               }
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I know I could set

$count{$1}=1
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but this is not desirable since I would like to add to the hash the counts of unique occurrences of other strings. For example:

$str1="abad";
$str2="aaab";
$n=2;
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should give the following list:
aa 1
ab 2
ad 1
ba 1
Thanks!