I have an android sudoku app and I'm doing the following to check if the generated sudoku is unique:
But there is a problem. I have six difficulty levels and each one has different number (The harder the more) of random hidden values. But this doesn't guarantee the real difficulty of each level.
Does anyone know a solution for this?
The solution is to use Andrew Stuart's sudoku solver on SudokuWiki.
Other automatic solvers will solve the sudoku as a computer would, trying all possible values for each cell, like a brute-force attack.
Andrew's solver solves it as a human would, by employing strategies of logical deduction. The strategies are ranked by "difficulty", which takes into account both how likely it is that the (human) solver knows the strategy and how likely the solver is to notice that it can be applied in this puzzle. You can use the Take Step button to have the solver use one strategy at a time to examine the solve path, or you can click on Grader to ask the solver what it thinks about how difficult your puzzle is.
