Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, and Clifford Stein, Introduction to Algorithms: Second Edition, MIT Press, 2001. ISBN: 0-07-013151-1.
or the first edition
Thomas H. Cormen, Charles E. Leiserson, and Ronald L. Rivest, Introduction to Algorithms, MIT Press, 1990.
De facto standard algorithms textbook. Encyclopedic and verbose. Not currently used in CS365, although it has been in the past. Currently dominates all other algorithms textbooks except KnuthSeries by sheer weight, though SedgewickSeries may displace both when completed.