* [500 Data structures and algorithms interview questions and their solutions in C++](https://www.quora.com/q/techiedelight/500-Data-Structures-and-Algorithms-interview-questions-and-their-solutions)
* [500 Data structures and algorithms interview questions and their solutions in C++](https://www.quora.com/q/techiedelight/500-Data-Structures-and-Algorithms-interview-questions-and-their-solutions)
* [A2 Online Judge](https://a2oj.com/ps)
* [A2 Online Judge](https://a2oj.com/ps)
* [Advent Of Code](http://adventofcode.com)
* [Advent Of Code](http://adventofcode.com)
* [AdventJS - 25 días de retos con JavaScript](https://adventjs.dev) - Miguel Ángel Durán «midudev» *(GitHub account requested, not required)*
* [Anarchy Golf](http://golf.shinh.org)
* [Anarchy Golf](http://golf.shinh.org)
* [APL Practice Problems](https://problems.tryapl.org)
* [APL Practice Problems](https://problems.tryapl.org)