Here is my collection of standard sized Sudoku test puzzles: https://github.com/jcoffland/fsudoku/tree/master/puzzles https://github.com/jcoffland/fsudoku/tree/

Here is my collection of standard sized Sudoku test puzzles: https://github.com/jcoffland/fsudoku/tree/master/puzzles https://github.com/jcoffland/fsudoku/tree/master/puzzles Some of these are the hardest possible puzzles, with a solution, for the size.