finish backtracking algo

sudoku/train.py

@@ -870,7 +870,7 @@ class SudokuTrialErrorLightning(SudokuLightning):
         return is_valid, new_x
         """
         try:
-            x = self.predict(x)
+            next_x = self.predict(x)
         except TrialEveryPosException:
             pos = self.search_trial(x.view(2,729), [])
             new_x = deepcopy(x.view(2,729))
@@ -883,7 +883,15 @@ class SudokuTrialErrorLightning(SudokuLightning):
             new_x[0,trial_abs_pres,pos]=1
             is_valid, new_x = self.backtracking_predict(new_x)
             if not is_valid:
-                return is_valid ### TO continue
+                new_x = deepcopy(x.view(2,729))
+                new_x[0,(trial_abs_pres+1)%2,pos]=1
+                return self.backtracking_predict(new_x)
+            return True, new_x
+        except ValueError:
+            return False, None
+        if next_x.sum()==729:
+            return True, next_x
+        return self.backtracking_predict(next_x)
             
     
     def on_validation_epoch_start(self) -> None: