public static Puzzle CreateSolvable()
{
var puzzle = CreateEmptyPuzzle();
var scratchpad = new PuzzleGeneratorState();
SetPuzzleBox(puzzle, scratchpad);
var i = 0;
while (i < 35)
{
var index = RandomNumberThinger.Instance.PickAValue(81);
if (puzzle.AllBoxes[index].IsGiven)
{
continue;
}
var givenBox = puzzle.AllBoxes[index];
givenBox.Guessed = givenBox.Assigned;
givenBox.IsGiven = true;
i++;
}
return(puzzle);
}
private static void SetPuzzleBox(Puzzle puzzle, PuzzleGeneratorState scratch)
{
if (scratch.CurrentIndex == 81)
{
return;
}
var possibles = puzzle.GetPossiblesForId(scratch.CurrentIndex);
while (possibles.Count > 0 && scratch.CurrentIndex < 81)
{
var selector = RandomNumberThinger.Instance.PickAValue(possibles.Count);
puzzle.SetValueAtId(scratch.CurrentIndex, possibles[selector]);
possibles.RemoveAt(selector);
scratch.CurrentIndex++;
SetPuzzleBox(puzzle, scratch);
if (scratch.CurrentIndex == 81)
{
return;
}
puzzle.ReleaseValueAtId(--scratch.CurrentIndex);
}
}
