feat: add algorithm book (#9902)

books/free-programming-books-subjects.md

@@ -92,6 +92,7 @@ Books that cover a specific programming language can be found in the [BY PROGRAM
 * [A Field Guide To Genetic Programming](https://web.archive.org/web/20191020195105/http://www0.cs.ucl.ac.uk/staff/W.Langdon/ftp/papers/poli08_fieldguide.pdf) - Riccardo Poli, William B. Langdon, Nicholas F. McPhee (PDF) *(:card_file_box: archived)*
 * [Algorithm Design](https://archive.org/details/AlgorithmDesign1stEditionByJonKleinbergAndEvaTardos2005PDF) - Jon Kleinberg, Éva Tardos
 * [Algorithmic Graph Theory](https://code.google.com/p/graphbook/) - David Joyner, Minh Van Nguyen, David Phillips (PDF)
+* [Algorithmic Thinking](https://labuladong.gitbook.io/algo-en) - Donglai Fu
 * [Algorithms](https://en.wikibooks.org/wiki/Algorithms) - Wikibooks
 * [Algorithms, 4th Edition](http://algs4.cs.princeton.edu/home/) - Robert Sedgewick, Kevin Wayne
 * [Algorithms and Automatic Computing Machines (1963)](https://archive.org/details/Algorithms_And_Automatic_Computing_Machines) - B. A. Trakhtenbrot