Sudoku is a logic-based combinatorial number-placement puzzle. The objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 sub-grids that compose the grid contains all of the digits from 1 to 9.
This exercise was taken from upcase.com. Validator takes a representation of a sudoku grid as a string and validates whether or not the grid is valid, valid but incomplete, or invalid. A sudoku grid is valid if:
- It has no duplicates in a row.
- It has no duplicates in a column.
- It has no duplicates in sub-group(one of the smaller 3x3 grids).
0 represents an empty spot. An example of a grid below.
8 5 0 |0 0 2 |4 0 0
7 2 0 |0 0 0 |0 0 9
0 0 4 |0 0 0 |0 0 0
------+------+------
0 0 0 |1 0 7 |0 0 2
3 0 5 |0 0 0 |9 0 0
0 4 0 |0 0 0 |0 0 0
------+------+------
0 0 0 |0 8 0 |0 7 0
0 1 7 |0 0 0 |0 0 0
0 0 0 |0 3 6 |0 4 0
To set up locally
git clone https://github.com/alejandroereyes/sudoku_validator.git
cd sudoku-validator
bin/setup
To run tests
bundle exec rspec spec
I broke out a module, ValidSudoku::Collection as the meat and potatoes for validation logic. I also broke out the Sudoku::Extract class to take in the sudoku grid string and convert it into collections representing rows, columns, and sub-groups. I added tests for these and the integration specs cover the complete logic executed by the validator.