Textbook in PDF format

If you want to upgrade your programming skills, the most important thing you need is a solid understanding of fundamental data structures. The proper choice of data structures distinguishes excellent programmers from merely competent ones.
As an experienced programmer, you use data structures―at least arrays―all the time. However, you may not be familiar with hash tables, trees and binary trees, priority queues, directed and undirected graphs, and other data structures at your disposal.
A good choice of data structures will simplify your job, not complicate it. Your code will be not only faster but also easier to understand and debug. There is no downside to using the right data structures for the job.
This book
Provides an understanding of the fundamental building blocks of data structures
Describes the construction and use of all common data structures
Explains the simple math required for selecting efficient data structures
Equips you with everything you need to choose data structures or devise appropriate new ones