This fourth edition of Robert Sedgewick and Kevin Wayne's Algorithms is one of the most popular textbooks on algorithms today and is widely used in colleges and universities worldwide. The algorithms in this book - including 50 algorithms every programmer should know - represent a body of knowledge developed over the last 50 years that has become indispensable, not just for professional programmers and computer science students but for any student with interests in science, mathematics, and engineering and for students who use computation in the liberal arts. In this edition, new Java implementations are written in an accessible modular programming style, where all of the code is exposed to the reader and ready to use. The companion web site, algs4.cs.princeton.edu, contains: An online synopsis Full Java implementations Test data Exercises and answers Dynamic visualizations Lecture slide.