So, I started Programming Challenges. I started with the first problem in the book, 100.
Submission 1: Wrong Answer.
Oops. Dumb numeric assumption.
Submission 2: Wrong Answer.
Huh. Oh. Right. Dumb input assumption.
Submission 3: Solved.
So, that did a nice job of knocking me down a peg.
For the morbidly curious, I put my solution up with mistakes commented.