Textbook for graduate number theory I am attending a graduate number theory, the professor did not assign any textbook. The materials are somewhere along the advanced/algebraic level such as Ring of Gaussian Integers, Quadratic Number Fields and especially about Euclidean Domain. Any suggestion to textbooks that I can read for self study? I prefer books that has lots of problems and their worked out solutions. Thank you for your time and help.

I can recommend some general graduate level texts,but it sounds from your question you're specifically looking for books with an algebraic bent.There aren't that many algebraic number theory texts-you'd think there would be, but it seems to be a fairly specialized-if important-area of mathematics. Algebraic Number Theory by Jürgen Neukirch is considered by most people I know to be the best of the modern algebraic number theory textbooks and it has a lot of exercises. There's also the classic book by Serge Lang of the same title,but it may be a bit out of date by now. Remember, to learn this subject you really need a very good grasp of basic algebra, particularly Galois theory, so it might be a good idea to consult a text on field theory. My favorite is Morandi's wonderful book. 
