I was looking for some good books for algebra and number theory at the olympiad level. Does anybody have any suggestions? I specifically want books that work on techniques and concepts (not just problems) and start out from a pretty accessible level and steadily build up to the desired level. An example of such a book would be 'A School Geometry' by H.S Hall and F.H. Stevens which has good problems as well as theory; and covers basic geometry quite well.
I tried out 'Problem Solving Strategies' by Arthur Engel, but that's just way over my level. I have trouble understanding the solutions presented in the book and the motivations behind them. I suspect I need to start at a simpler level.