You don't need to be well versed in reinforcement learning "a-priori" knowledge or worry about opponents moves or "optimal tabular and minimax solutions" or branching factors or anything else.

Start with a text file of every combination separated by lines.

RRRRR RRRRG RRRGG

Then use cat to output it to grep and use grep for all the constraints.

One for colors that aren't there. One for colors you know are in the right place. Then after that one grep for every color you know is there somewhere and one for each color you know isn't in a certain spot.

cat combinations.txt | grep -v [colors that aren't there] | grep ..R.G | grep B | grep -v .Y...

That's it. All you need is a command line. Generate guesses from the filtered list then add to the filters.