C++ Question. I need help writing the function below which is meant to take the letters "A", "B", and "C" and output all the various combinations without duplicates. n is the length of each combination. All help is appreciated and helper functions are allowed.

unsigned combABC(unsigned n); combABC outputs each combination of n letters, where each letter is A, B, or C. For example, combABC(4) would output 15 lines: AAAB /or it could just as well output ABAA, since that's the same combination AAAC AABB AABC AACC ABBB ABBC ABCC ACCC BBBC BBCC BCCC combABC should also return the number of combinations; it should be the number of combinations by computation, not just counting how many lines of output it produces