Find all combinations of values in a dataframe column and optimize based on values in a different column

Question

I have a dataframe with the following structure:

|code|score|slots|
|a   |50   |0.25 |
|b   |66   |0.33 |
|c   |20   |0.20 |
|d   |28   |0.20 |
|e   |23   |0.