If by "computer science" you mean "programming", then Knuth's series is indispensable, and an excellent addition would be Aho, Hopcroft, and Ullman's "Design and Analysis of Computer Algorithms".
On the other hand, if by "computer science" you mean the branch of mathematics that goes by this name, the best text I know if is Machtey & Young's "Introduction to the general theory of algorithms". Sadly, this book is out of print (few people use use this meaning of "computer science" any more), but right now there are used copies available at amazon. Another excellent book in this category would be Garey & Johnson's "Computers and Intractability: A Guide to the Theory of NP-Completeness". A final text worth looking at is Michael Sipser's "Introduction to the Theory of Computation" (you can save some $$ by purchasing one of the older editions).