* remove main() and make n_queens a header file
* move functions inside NQueensSolver class

and drop ".test" from tests

and update unit test

* add commands for installing CMake 3.10
* update build command

and add build entry in CMakeLists

* call solve() in the constructor to guarantee that the puzzle has been solved when calling any public method
* show_solution -> print_solution

…#200)

Importing the `std` namespace can lead to namespace pollution. This commit replaces those namespace directives with more specific ones, such as `using std::cin`.

Refactor greatest common denominator algorithm to use a header file. Add test
cases as .cpp file to test. Also fix an error in greatest common denominator
function that prevented the accurate calculation of negative arguments. Update
README.

* Migrate extended Euclidean to header, unit tests

Removes old .cpp file for the extended Euclidean algorithm and adds unit
 tests. Also updates README.

* Fix accidental addition of old denominator files