removed double connection

window.cpp

@@ -53,11 +53,12 @@ Window::Window(QWidget *parent)
             for (int d = 0; d < 9; d++) // rows and columns
             {
                 connect(&grid[x + y * 9], SIGNAL(update(int)), &grid[x + d * 9], SLOT(removeOption(int)));
-                connect(&grid[x + y * 9], SIGNAL(update(int)), &grid[d + y * 9], SLOT(removeOption(int)));
-
                 connect(&grid[x + y * 9], SIGNAL(undo(int)), &grid[x + d * 9], SLOT(addOption(int)));
+                if(&grid[x+y*9]!= &grid[d+y*9]){
+                    connect(&grid[x + y * 9], SIGNAL(update(int)), &grid[d + y * 9], SLOT(removeOption(int)));
                     connect(&grid[x + y * 9], SIGNAL(undo(int)), &grid[d + y * 9], SLOT(addOption(int)));
                 }
+            }
             int a = x / 3 * 3;
             int b = y / 3 * 3;
             for (int x1 = a; x1 < a + 3; x1++) // square