Finding all the unique permutations of a string without generating duplicates

Question

Finding all the permutations of a string is by a well known Steinhaus–Johnson–Trotter algorithm. But if the string contains the repeated characters such as
AABB,
the

Answer 1

Use the following recursive algorithm:

PermutList Permute(SymArray fullSymArray){
    PermutList resultList=empty;
    for( each symbol A in fullSymArray, but repeated ones take only once) {
       PermutList lesserPermutList=  Permute(fullSymArray without A)
       for ( each SymArray item in lesserPermutList){
            resultList.add("A"+item);
       }
    }
    return resultList;
}

As you see, it is very easy