I want to tell you about a group of students I particularly enjoy working with. I'm not going to tell you their names since I don't think it's appropriate for me to talk about people in the class with the rest of the class. But I'll tell you why I like working with them.

They are a group of three people. They always work together on the assignments. They seem to work very hard, and they generally come up with solutions of some sort. (At least two of the three seem to understand the solutions. It's not just one person doing all the work. I'm often not sure about the extent to which the third person contributes, though.)

They generally don't solve all the problems, and their solutions to the problems they solve are often not very elegant.

But they have spent enough time thinking about the problems that we can take their solutions and make them more elegant. They understand how the changes we make work and why they make sense. 

Even for the problems they don't solve, they have put enough effort into solving them that with a bit of discussion they can see how to finish the solutions that we sketch out.

As you can see, as far as I'm concerned, it's fine to work together. It's also fine not to find solutions to all the problems. What's most important is that you spend enough time and effort working on the problems so that when we discuss them, we can build on the work you have already done -- and, of course, that you understand that work well enough that we can use it as a basis for our discussion.