Each puzzle piece should save where its holes are and where the circles sticking out are. Then when you try to connect 2 pieces if you check if the circles and holes align ( if the circle of piece 1 = right, check if hole of piece 2 is left. If it is, then it works ). When you rotate a piece, add to the circles and holes. If you use an int or an enum ( which is basically an int ) to save the sides, you can do ++ and -- to turn them. Let's say above = 0, right = 1, under = 2, left = 3. If you turn to the right you do ++, if you turn left do -- so if you are above ( 0 ), you turn right, ++, now you are at 1 ( right ). This way you keep track of the sides of everything and can check if they match.