* SudokuSolver::ComputeSolutions() can now be called more than once without

doubling the solution list.
* ComputeSolutions() will now check if solving the Sudoku is affordable for
  this algorithm (at least 1/6th of the fields must be known). This fixes
  one part of bug #1435.
* SudokuView now checks if the Sudoku is already solved before trying to
  fill in a value from the solution (and then it did not find a free spot,
  surprisingly). This fixes the other part of bug #1435.
* SudokuView now beeps if there was no solution.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22110 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/apps/sudoku/SudokuSolver.cpp

@@ -144,7 +144,13 @@ SudokuSolver::SudokuSolver()
 SudokuSolver::~SudokuSolver()
 {
 	// we don't own the field but the solutions
+	_MakeEmpty();
+}
 
+
+void
+SudokuSolver::_MakeEmpty()
+{
 	for (uint32 i = 0; i < fSolutions.size(); i++) {
 		delete fSolutions[i];
 	}
@@ -161,6 +167,20 @@ SudokuSolver::SetTo(SudokuField* field)
 void
 SudokuSolver::ComputeSolutions()
 {
+	_MakeEmpty();
+
+	// We need to check if generating a solution is affordable with a
+	// brute force algorithm like this one
+	uint32 set = 0;
+	for (uint32 y = 0; y < fField->Size(); y++) {
+		for (uint32 x = 0; x < fField->Size(); x++) {
+			if (fField->ValueAt(x, y))
+				set++;
+		}
+	}
+	if (set < fField->Size() * fField->Size() / 6)
+		return;
+
 	Stack<SolutionStep*> stack;
 	SolutionStep* step = new SolutionStep(fField);
 	step->ToFirstUnset();

src/apps/sudoku/SudokuSolver.h

@@ -26,6 +26,8 @@ public:
 	SudokuField* SolutionAt(uint32 index);
 
 private:
+	void _MakeEmpty();
+
 	typedef std::vector<SudokuField*> SudokuList;
 
 	SudokuField*	fField;

src/apps/sudoku/SudokuView.cpp

@@ -15,6 +15,7 @@
 #include <stdlib.h>
 
 #include <Application.h>
+#include <Beep.h>
 #include <File.h>
 #include <Path.h>
 
@@ -617,12 +618,18 @@ SudokuView::MessageReceived(BMessage* message)
 			if (solver.CountSolutions() > 0) {
 				fField->SetTo(solver.SolutionAt(0));
 				Invalidate();
-			}
+			} else
+				beep();
 			break;
 		}
 
 		case kMsgSolveSingle:
 		{
+			if (fField->IsSolved()) {
+				beep();
+				break;
+			}
+
 			SudokuSolver solver;
 			solver.SetTo(fField);
 			bigtime_t start = system_time();
@@ -640,7 +647,8 @@ SudokuView::MessageReceived(BMessage* message)
 				fField->SetValueAt(x, y,
 					solver.SolutionAt(0)->ValueAt(x, y));
 				_InvalidateField(x, y);
-			}
+			} else
+				beep();
 			break;
 		}