There are some exercise solutions from Cracking the Coding Interview: 189 Programming Questions and Solutions by Gayle Laakmann McDowell.
They are grouped by chapters. Every exercise contains PHPUnit test file in /tests folder, if possible. You can run it with vendor/bin/phpunit tests command. Also every exercise folder has its own README.md with description.
Before running PHPUnit tests you need to install required packages with composer install
I hope this project helps to the beginners to understand how the exercises from this book are solved using PHP language.