Two grids are shown below. Each grid contains a robot represented as a triangle. Both robots are initially facing left. Each robot can move into a white or gray square, but cannot move into a black region.

For each grid, the program below is intended to move the robot to the gray square. The program uses the procedure Goal_Reached (), which evaluates to true if the robot is in the gray square and evaluates to false otherwise.

• REPEAT UNTIL (Goal_Reached ())
• {
•   IF (CAN_MOVE (right))
•   {
•     ROTATE_RIGHT ()
•   }
•   ELSE
•   {
•     IF (CAN_MOVE (left))
•     {
•       ROTATE_LEFT ()
•     }
•   }
•   IF (CAN_MOVE (forward))
•   {
•     MOVE_FORWARD ()
•   }
• }

For which of the grids does the program correctly move the robot to the gray square?

Summary Submit Skip Question

The program first checks if the robot can move right. If it can, it does. Afterwards, it does this for the left direction. Then the robot moves forward as much as possible.

Grid I and II are similar, but the robot will only reach the gray square for Grid I. In Grid II, the robot will end up in the top right square. This is because the robot rotates right if possible before going left. At the last junction, the robot would therefore rotate right and move into the wrong final square.