Kill Sudoku Step by Step description

* solve sudoku step by step to learn how to solve sudoku puzzle
* current support technique:Naked Single, Hidden Single, Pointing, Claiming, Naked Subset, Hidden Subset, X-Chains, XY-Chains, XYZ-Chains

Please note: if the input puzzle is not valid then you can get a correct result, or if the puzzle you input is too hard to solve by the utility then you won't get a correct result either.

Source code is available at https://github.com/cnyaw/ks