My answer may be a little off-topic.
Well, you got the problem as I did when I was a high school student. Even when I was a freshmen, I would like to find the "materials that do provide all answers to problems so that I can feel comfortable that I am solving the problems correctly" exactly as you do now. However, my experience tells me that it may be harmful to do so.
On the one hand, it is very possible to lead to one's laziness if he/she has the complete solution books. After all, one seldom wants to go through a "hard time" for problem solving, which I think is quite instructive and necessary, when one has the solutions by hand.
On the other hand, there is no solution at all when you do research problem or solve the problem in your real life. What you need to do then is tell the correctness of your own solutions yourself instead of referring to a solution manual. In the spirit of Polya, one should be able to check his/her own answer himself/herself. And it is a very good chance to practice this skill when you do elementary exercises.
Actually, almost every textbook contains answers to some special "exercises". Think about the theorems and examples in the book. You can regard them as exercises and check your solutions by reading the book. Finally, you can convince yourself that you don't need "all answers" to check your solution. Why? Think about the arithmetics you learned. Do you still need a solution manual to check?