I guess I have to do something new today: agree with Scott.
I used K&R and then the wonderful Algorithms and Data Structures I, II, and III by Sedgewick (Original C versions).
Seem to me to both be pretty good, though you'll have to read over "Algorithms" a lot, sometimes, in order to make sense of Sedgwick's ridiculously truncated code. Of course, sometimes I wonder how useful the data structures are, since Cocoa pretty much gives 'em to ya. Bah. Sometimes you just need to roll your own for SPEED.
I am a fan of Cocoa because I don't like OO too much. The way objective C approaches it, though, makes it more straightforward to me than the way C++ and Java do it. However, the caveat is that you'll want to get some sort of smalltalk primer if you want to save some time trying to decypher and figure out the syntax of the OO calls in Cocoa.