Although point #3 has also annoyed me no end, I believe I learned a lot from being forced to solve problems myself. Peeking at the solution is just too easy and

Although point #3 has also annoyed me no end, I believe I learned a lot from being forced to solve problems myself. Peeking at the solution is just too easy and severely diminishes what you can learn by being forced to think more about the problem. I believe Introduction to the Theory of Computation by Sipser gets it right: answers to about half the exercises.