Every room has either 3,6,9, or 12 rocks in it, and every room has 4 exits. If there were 3 rocks in the room you would take the right exit. It's positioned like a clock. 3 is on the right side of the room, 6 is on the bottom, 9 on the left, and 12 on top. Did this help you?
EDIT: nevermind you just posted and you figured it out.