This article was my crash course for computer science (I come from another engineering field). I learned so much by studying this code, and understanding it allowed me to write a sudoku generator. The generator algorithm is much different than solving, but the basic structure was already there for me.

In any case, I'm replying to your comment because it applies to me. Norvig's code is compact and elegant, whereas mine is spaghetti code at best. I basically have lots of control statements, as there are many many processing steps that I painstakingly discovered as I went along (thousands of lines). Heck, I can barely remember them myself.

Here's my site: http://sudokuisland.com