Fixed 3 issues with DSA books address titles and books

Author: Colm Woods

books/free-programming-books-subjects.md

@@ -98,7 +98,6 @@ 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)* (CC BY-NC-ND)
 * [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) (GFDL)
-* [Algorithmic Problem Solving](https://www.cs.ox.ac.uk/jeremy.gibbons/wg21/meeting58/backhouse-problems.pdf) - Roland Backhouse (PDF)
 * [Algorithmic Thinking](https://labuladong.gitbook.io/algo-en) - Donglai Fu
 * [Algorithms](https://en.wikibooks.org/wiki/Algorithms) - Wikibooks
 * [Algorithms](https://jeffe.cs.illinois.edu/teaching/algorithms/book/Algorithms-JeffE.pdf) - Jeff Erickson (PDF)
@@ -115,14 +114,13 @@ Books that cover a specific programming language can be found in the [BY PROGRAM
 * [Data Structures](https://adityacse.weebly.com/uploads/2/4/0/7/24078687/data-structures.pdf) - Aditya CSE (PDF)
 * [Data Structures](https://en.wikibooks.org/wiki/Data_Structures) - Wikibooks
 * [Data Structures and Algorithm Analysis in C++](https://people.cs.vt.edu/~shaffer/Book/C++3elatest.pdf) - Clifford A. Shaffer (PDF)
+* [Data Structures and Algorithm Analysis in Java](https://people.cs.vt.edu/~shaffer/Book/JAVA3elatest.pdf) - Clifford A. Shaffer (PDF)
 * [Data Structures and Algorithms: Annotated Reference with Examples](https://web.archive.org/web/20170715160229/http://dotnetslackers.com/Community/files/folders/data-structures-and-algorithms/entry30283.aspx) - G. Barnett, L. Del Tongo *( :card_file_box: archived)*
-* [Data Structures and Functional Programming (Thesis Version)](https://www.cs.cmu.edu/~rwh/students/okasaki.pdf) - Chris Okasaki (PDF)
 * [Data Structures Succinctly Part 1, Syncfusion](https://www.syncfusion.com/resources/techportal/ebooks/datastructurespart1) - Robert Horvick
 * [Data Structures Succinctly Part 2, Syncfusion](https://www.syncfusion.com/resources/techportal/ebooks/datastructurespart2) - Robert Horvick
 * [Elementary Algorithms](https://github.com/liuxinyu95/AlgoXY) - Larry Liu Xinyu (PDF)
 * [Essential Algorithms](https://www.programming-books.io/essential/algorithms/) - Krzysztof Kowalczyk and Stack Overflow Documentation project (HTML)
 * [Foundations of Computer Science](http://infolab.stanford.edu/~ullman/focs.html) - Al Aho, Jeff Ullman
-* [Introduction to Algorithms and Data Structures](https://people.cs.vt.edu/shaffer/Book/JAVA3elatest.pdf) - Clifford A. Shaffer (PDF)
 * [Learning Algorithm](https://riptutorial.com/Download/algorithm.pdf) - Compiled from StackOverflow documentation (PDF) (CC BY-SA)
 * [Lectures Notes on Algorithm Analysis and Computational Complexity (Fourth Edition)](https://ianparberry.com/books/free/license.html) - Ian Parberry (use form at bottom of license)
 * [LEDA: A Platform for Combinatorial and Geometric Computing](https://people.mpi-inf.mpg.de/~mehlhorn/LEDAbook.html) - K. Mehlhorn, St. Näher
@@ -131,8 +129,9 @@ Books that cover a specific programming language can be found in the [BY PROGRAM
 * [Matters Computational: Ideas, Algorithms, Source Code](https://www.jjj.de/fxt/fxtbook.pdf) - Jörg Arndt (PDF)
 * [Open Data Structures: An Introduction](https://opendatastructures.org) - Pat Morin
 * [Planning Algorithms](http://lavalle.pl/planning/) - Steven M. LaValle
+* [Principles of Algorithmic Problem Solving](https://www.csc.kth.se/~jsannemo/slask/main.pdf) - Johan Sannemo (PDF)
 * [Problems on Algorithms (Second Edition)](https://ianparberry.com/books/free/license.html) - Ian Parberry (use form at bottom of license)
-* [Purely Functional Data Structures (1996)](https://web.archive.org/web/20210917054102/http://www.cs.cmu.edu/~rwh/theses/okasaki.pdf) - Chris Okasaki (PDF) *( :card_file_box: archived)*
+* [Purely Functional Data Structures](https://www.cs.cmu.edu/~rwh/students/okasaki.pdf) - Chris Okasaki (PDF)
 * [Sequential and parallel sorting algorithms](https://www.inf.hs-flensburg.de/lang/algorithmen/sortieren/algoen.htm) - Hans Werner Lang (HTML)
 * [Text Algorithms](https://igm.univ-mlv.fr/~mac/REC/text-algorithms.pdf) - Maxime Crochemore, Wojciech Rytter (PDF)
 * [The Algorithm Design Manual](https://www8.cs.umu.se/kurser/TDBAfl/VT06/algorithms/BOOK/BOOK/BOOK.HTM) - Steven S. Skiena (HTML)
@@ -143,6 +142,7 @@ Books that cover a specific programming language can be found in the [BY PROGRAM
 * [Think Complexity (2nd Edition)](https://greenteapress.com/wp/think-complexity-2e/) - Allen B. Downey
 
 
+
 ### Artificial Intelligence
 
 * [AI Safety for Fleshy Humans](https://aisafety.dance) - Nicky Case and Hack Club *( :construction: in process)* (CC BY-NC)