<p>First of all I would look at WHY you want to double-major in CS again. What was your goal when you decided to do it? Is it just that you are interested in it? Do you think it will give you more/better job opportunities? Better chances for grad school admission? What do you think how important this double major is actually for your further career? If you’re simply interested in CS, you could as well study these things on your own. As someone who studied almost everything on his own, I can tell you that it’s far from impossible. There are tons of good resources out there (Lectures/Courses from Berkeley/MIT online, great books, etc). However, if you want to work after undergrad. school, there will probably be more job opportunities for someone with a CS Degree than for someone with a pure math degree. For grad school it might not matter that much…</p>
<p>If you think that the CS double major would be really helpful in your future career, I would take the easy professor. You might think you don’t learn as much, but the truth is that how well you learn is up to you. That your professor does not teach well/much, does not mean that you can’t read other books which actually teach you the material at the same time. </p>
<p>If you only worked with Python and don’t know much about Data Structures anymore, then yeah, I think it would be hard to study both of these over the summer. On the other hand I think that Java is a very important language and that someone who was a minor in CS should know about it. If you have a CS Degree and only know Python, I guess that it would look a little strange to a possible employer.</p>