I credit teachers more than books but a partnership between teachers and books makes education great.

I found "Introduction to Algorithms" [1] very accessible for a CS student and also "Introduction to Automata Theory, Languages, and Computation" [2] very complete.

[1] https://www.amazon.com/Introduction-Algorithms-3rd-MIT-Press...

[2] https://en.wikipedia.org/wiki/Introduction_to_Automata_Theor...