Add knapsack

[ryanplusplus]

Related to #940

[siebenschlaefer]

Just in case you were waiting for a review: Looks great!
(I don't think I have the power to approve here on the C track.)

The only tiny suggestion from me is this:
In the first test you could consider defining variables items and item_count, just like in the other tests, because the students have to extract the signature and semantics of the function maximum() from the tests and I think that's easier with maximum(maximum_weight, items, item_count) than with maximum(maximum_weight, NULL, 0).

[ryanplusplus]

Just in case you were waiting for a review: Looks great! (I don't think I have the power to approve here on the C track.)

The only tiny suggestion from me is this: In the first test you could consider defining variables items and item_count, just like in the other tests, because the students have to extract the signature and semantics of the function maximum() from the tests and I think that's easier with maximum(maximum_weight, items, item_count) than with maximum(maximum_weight, NULL, 0).

Good point, I'll change that.

[ryanplusplus]

Just in case you were waiting for a review: Looks great! (I don't think I have the power to approve here on the C track.)

Thanks for the review!