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Ace the AP Computer Science Exam for High Schoolers

Solution Review: Car Parking Robot

Explore how to build a car parking robot in Java by using nested loops to navigate a parking lot grid. Learn to control iterations, apply conditional checks for parking spots, and track parked cars. This lesson helps you grasp core iteration patterns and practical problem-solving for programming projects.

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Rubric criteria

Solution

Java
class CarParking 

{

    public static void main(String args[]) 

    {

         robot(10, 10, 19);

    }



    public static void robot(int width, int length, int cars)

    {

        int counter = 0;                            // Number of parked cars

        for (int i = 0; i < length; i++)

        {

            for (int j = 0; j < width; j++)         // Filling row-wise

            {

                if (j % 4 == 0)                     // Leaving three columns 

                {

                    if (counter < cars)            // If any car left

                    {

                         System.out.print("🚗");    // Parking the car

                         counter++;

                    }

                    else                            // No car left

                    {

                        System.out.print("🚫");     // Marking space as available

                    }

                }        

                else                               // distance less than 3 meters

                {

                    System.out.print(" ");         // Adding the space

                }                 

            }

            System.out.print("\n");                // Row completed, move to next row

        }

    }

}

Rubric-wise explanation

Point 1:

Look at the header of the robot() function at line 8. It takes the width and the length of the car parking lot. Additionally, it also accepts the number of cars needed to be parked: cars.

Point 2, 3:

We need to keep track of cars that are parked by the robot. We made the int variable, counter, for this purpose. According to the challenge, the robot needs to advance width-wise. We make a nested loop. The outer loop (at line 11) controls the vertical propagation (movement along the rows) of the robot, whereas, the inner-loop (at line 13) controls the horizontal propagation (movement ...