I think Problem-Solving Strategy is an interesting book for teens. It does not need a deep mathematical background. However, if its math is too hard you can find an interesting and small book about discrete mathematics¹ to read first and then switch back to this book. I read it when I was in high school and this book motivated me to do stuff in CS.
- I think what constitutes a discrete mathematics book for teens depends on native culture and language. I know a good one in my language, but I do not know any good ones in other languages.
