I am looking for the canonical implementation of the "k-combinations with repetition" algorithm.
Input: "ABC" (choose 2)
['AA', 'AB', 'AC', 'BB', 'BC', 'CC']
I have a recursive implementation, I'm looking for the performance optimized state of the art version. Usually people mention Knuth for this, but I haven't seen a specific reference to Vol 4a or otherwise for this particular one. Not to say it isn't there, just haven't found any references to it.
Where might I look further into this?