CareerCup

A class "ParkingLot" would be an aggregate of "ParkingSpot".
The other main class would be the "ParkingEntryGate" at which you need collect a "Ticket".
The ParkingEntryGate would maintain the details of the "Vehicle" and the time in.
Another good feature would be a "FreeParkingSpotBillboard" which notifies people as to which parking spots are free. The "ParkingSpot" would be associated with a unique id.
Another Entity would be the "Customer" who has a "Vehicle" and a "Ticket". There would be a method named GetCustomerDetails inside "ParkingLot" which would tell us the details of time spent inside parking for each customer by date. Every customer would have a unique id.
Basically one needs to conceptualize the various entities and make a domain driven design.
(This could be used at the Parking Entry Gate with a front end of a web application if required.)

Watch "Mission Impossible: Ghost protocol" ending part
for a reasonably good design. Btw, the movie rocks!

any more?

class ParkingLot
{
private:
    string name;
    string address;
    int Capacity;
    int Used;

public:
    // how many spaces left in the parkinglot
    int GetSpaces();

    // how many spaces left 
    // enum {compact = 0, mid, ...}
    int GetSpaces(int size);

    // total spaces parkinglot has
    int GetCapacity();

    // if the parkinglot is opened
    bool IsOpened();

    // return parkinglot open time of a specified date
    // e.g. "8:00 AM - 10:00 PM"
    string GetOpenTime(time_t date); 

    // fee $ per hour
    int ChargeMoney();

    // Get the address of parking lot
    string GetAddress();

    // get type of parkinglot
    // enum { outdoor = 0, ... };
    int GetType();

    string Name();
};

My solution (Didnt take time into consideration but can take it into consideration as a part of Vehicle class and calculating it in between the parkVehicle() and releaseVehicle() classes :

public class ParkingLot 
{
	Vector<ParkingSpace> vacantParkingSpaces = null;
	Vector<ParkingSpace> fullParkingSpaces = null;
	
	int parkingSpaceCount = 0;
	
	boolean isFull;
	boolean isEmpty;
	
	ParkingSpace findNearestVacant(ParkingType type)
	{
		Iterator<ParkingSpace> itr = vacantParkingSpaces.iterator();
		
		while(itr.hasNext())
		{
			ParkingSpace parkingSpace = itr.next();
			
			if(parkingSpace.parkingType == type)
			{
				return parkingSpace;
			}
		}
		return null;
	}
	
	void parkVehicle(ParkingType type, Vehicle vehicle)
	{
		if(!isFull())
		{
			ParkingSpace parkingSpace = findNearestVacant(type);
		
			if(parkingSpace != null)
			{
				parkingSpace.vehicle = vehicle;
				parkingSpace.isVacant = false;
			
				vacantParkingSpaces.remove(parkingSpace);
				fullParkingSpaces.add(parkingSpace);
				
				if(fullParkingSpaces.size() == parkingSpaceCount)
					isFull = true;
				
				isEmpty = false;
			}
		}
	}
	
	void releaseVehicle(Vehicle vehicle)
	{
		if(!isEmpty())
		{
			Iterator<ParkingSpace> itr = fullParkingSpaces.iterator();
			
			while(itr.hasNext())
			{
				ParkingSpace parkingSpace = itr.next();
				
				if(parkingSpace.vehicle.equals(vehicle))
				{
					fullParkingSpaces.remove(parkingSpace);
					vacantParkingSpaces.add(parkingSpace);
					
					parkingSpace.isVacant = true;
					parkingSpace.vehicle = null;
					
					if(vacantParkingSpaces.size() == parkingSpaceCount)
						isEmpty = true;
					
					isFull = false;
				}
			}
		}
	}
	
	boolean isFull()
	{
		return isFull;
	}
	
	boolean isEmpty()
	{
		return isEmpty;
	}
}

public class ParkingSpace 
{
	boolean isVacant;
	Vehicle vehicle;
	ParkingType parkingType;
	int distance;
}

public class Vehicle 
{
	int num;
}

public enum ParkingType
{
	REGULAR,
	HANDICAPPED,
	COMPACT,
	MAX_PARKING_TYPE,
}