Appendices A–C to CLRS
offer a brief review of everything you need to know about mathematics in order to successfully master IADS.
R. Johnsonbaugh. Discrete Mathematics. 5th ed. Prentice–Hall (2001). ISBN 0-13-089008-1
A fat and very verbose book. If CLRS' Appendix is in places too skimpy, this may be a good place to get easy-step, detailed explanations. Lots of exercises. Johnsonbaugh's Appendix is good for recalling high-school algebra.
S. Washburn, T. Marlowe, C. T. Ryan. Discrete Mathematics. Addison–Wesley (2000). ISBN 0-201-88336-8
Covers essentially the same material as Johnsonbaugh, but spends much fewer words. (In the last chapter the authors are out of their depth, though.) For people who like concise accounts.
L. Lovász, J. Pelikán, K. Vesztergombi. Discrete Mathematics. Elementary and Beyond. Springer (2003). ISBN 0-387-95585-2
Good but not particularly low-level book. Written by algorithmically-minded authors. A preliminary version of this book is available.
J. A. Anderson. Discrete Mathematics with Combinatorics. 2nd ed. Prentice–Hall (2004). ISBN 0-13-045791-4
A very competent book covering considerably more material than you need for IADS at a healthy rhythm.
R. L. Graham, D. E. Knuth, O. Patashnik. Concrete Mathematics. 2nd ed. Addison–Wesley (1994). ISBN 0-201-55802-5
Much higher-level book. All kinds of sequences and series, Oh-large etc. Goes into some depth.
R. C. Penner. Discrete Mathematics. Proof Techniques and Mathematical Structures. World Scientific (1999). ISBN 981-02-4088-0
Does discrete mathematics as a pure mathematics discipline ("the right way"). Very careful with logic and proofs.