Could somebody direct me to an online and free available collection/s or resources of solved and commented (not necessarily) Lisp programming problems, especially related to binary trees and recursion.
I tried to Google it up the question but I didn't manage to find anything useful.
I need solved problems because in my attempt of learning Lisp I want to try to solve them and compare the result.
Thanks!
I don't have any specific examples, but this PDF is fantastic:
http://www.cse.buffalo.edu/~shapiro/Commonlisp/commonLisp.pdf
From the website of a former prof of mine.
Project Euler proved to be the best for me. It's not exclusively lisp though.
You have to register and solve the problem to see solutions of other people. Testing your solution is as easy as pasting the results to the site.
I ran into http://gigamonkeys.com/book/ this book recently. It's pretty modern.
Good book on Lisp by Paul Graham. It's also free.
L-99: Ninety-Nine Lisp Problems is also a great site for individual solving of Lisp problems. 99 problems and solutions included.
It's not exactly in the format you asked for, but the source code from AIMA might be of use to you.
The Rosetta Code project contains hundreds of solved problems in a variety of languages and dialects, including Lisp, Scheme, Clojure, etc.