Problem
Design a parking lot.
see CC150 OO Design for details.
- n levels, each level has m rows of spots and each row has k spots.So each level has m x k spots.
- The parking lot can park motorcycles, cars and buses
- The parking lot has motorcycle spots, compact spots, and large spots
- Each row, motorcycle spots id is in range [0,k/4)(0 is included, k/4 is not included), compact spots id is in range [k/4,k3/4) and large spots id is in range [k3/4,k].
- A motorcycle can park in any spot
- A car park in single compact spot or large spot
- A bus can park in five large spots that are consecutive and within same row. it can not park in small spots
Example
level=1, num_rows=1, spots_per_row=11 parkVehicle("Motorcycle_1") // return true parkVehicle("Car_1") // return true parkVehicle("Car_2") // return true parkVehicle("Car_3") // return true parkVehicle("Car_4") // return true parkVehicle("Car_5") // return true parkVehicle("Bus_1") // return false unParkVehicle("Car_5") parkVehicle("Bus_1") // return true
Solution
// enum type for Vehicle
enum class VehicleSize {
Motorcycle,
Compact,
Large,
Default
};
class Vehicle {
public:
virtual VehicleSize size() {
return VehicleSize::Default;
}
};
class Bus: public Vehicle {
public:
VehicleSize size() {
return VehicleSize::Large;
}
};
class Car: public Vehicle {
public:
VehicleSize size() {
return VehicleSize::Compact;
}
};
class Motorcycle: public Vehicle {
public:
VehicleSize size() {
return VehicleSize::Motorcycle;
}
};
class Level {
private:
vector<Vehicle* > motoSpots;
vector<Vehicle* > compactSpots;
vector<Vehicle* > largeSpots;
map<Vehicle*, map<VehicleSize, int>> vehicle2spot;
public:
Level(int num_rows, int spots_per_row) {
int motoSpotSize = spots_per_row / 4;
motoSpots.resize(motoSpotSize);
int compactSpotSize = spots_per_row * 3 / 4 - motoSpotSize;
compactSpots.resize(compactSpotSize);
int largeSpotSize = spots_per_row - spots_per_row * 3 / 4 + 1;
largeSpots.resize(largeSpotSize);
}
int canParkVehicle(Vehicle* vehicle, VehicleSize size, int num) {
if (size == VehicleSize::Motorcycle) {
for(int i = 0; i < motoSpots.size(); i++) {
if (motoSpots[i] == NULL) {
return i;
}
}
return -1;
} else if (size == VehicleSize::Compact) {
for(int i = 0; i < compactSpots.size(); i++) {
if (compactSpots[i] == NULL) {
return i;
}
}
return -1;
} else {
for(int i = 0; i < largeSpots.size(); i++) {
if (largeSpots[i] == NULL) {
bool flag = true;
for(int j = i; j < i + num; j++) {
if (largeSpots[i] != NULL) {
flag = false;
break;
}
}
if (flag) {
return i;
}
}
}
return -1;
}
}
void parkVehicle(Vehicle* vehicle, VehicleSize parkSpotType, int index, int num) {
if (parkSpotType == VehicleSize::Motorcycle) {
motoSpots[index] = vehicle;
} else if (parkSpotType == VehicleSize::Compact) {
compactSpots[index] = vehicle;
} else {
for(int i = index; i < index + num; i++) {
largeSpots[i] = vehicle;
}
}
vehicle2spot[vehicle][parkSpotType] = index;
}
void unParkVehicle(Vehicle *vehicle) {
map<VehicleSize, int> spot = vehicle2spot[vehicle];
VehicleSize size = vehicle->size();
int index = spot[size];
if (size == VehicleSize::Motorcycle) {
motoSpots[index] = NULL;
} else if (size == VehicleSize::Compact) {
compactSpots[index] = NULL;
} else {
for(int i = index; i < largeSpots.size(); i++) {
if (largeSpots[i] == vehicle) {
largeSpots[i] = NULL;
} else {
break;
}
}
}
}
};
class ParkingLot {
private:
vector<Level* > levels;
map<Vehicle*, Level*> vehicle2level;
public:
// @param n number of leves
// @param num_rows each level has num_rows rows of spots
// @param spots_per_row each row has spots_per_row spots
ParkingLot(int n, int num_rows, int spots_per_row) {
for(int i = 0; i < n; i++) {
Level *level = new Level(num_rows, spots_per_row);
levels.push_back(level);
}
}
// Park the vehicle in a spot (or multiple spots)
// Return false if failed
bool parkVehicle(Vehicle &vehicle) {
VehicleSize size = vehicle.size();
if (size == VehicleSize::Motorcycle) {
cout << "Moto" << endl;
if (!parkInMotoSpot(vehicle)) {
if (!parkInCompactSpot(vehicle)) {
return parkInLargeSpot(vehicle, 1);
}
}
return true;
} else if (size == VehicleSize::Compact) {
cout << "Compact" << endl;
if (!parkInCompactSpot(vehicle)) {
return parkInLargeSpot(vehicle, 1);
}
} else if (size == VehicleSize::Large) {
cout << "Bus" << endl;
return parkInLargeSpot(vehicle, 5);
} else {
return false;
}
}
bool parkInMotoSpot(Vehicle &vehicle) {
for(int i = 0; i < levels.size(); i++) {
int index = levels[i]->canParkVehicle(&vehicle, VehicleSize::Motorcycle, 1);
if (index != -1) {
levels[i]->parkVehicle(&vehicle, VehicleSize::Motorcycle, index, 1);
vehicle2level[&vehicle] = levels[i];
return true;
}
}
return false;
}
bool parkInCompactSpot(Vehicle &vehicle) {
for(int i = 0; i < levels.size(); i++) {
int index = levels[i]->canParkVehicle(&vehicle, VehicleSize::Compact, 1);
cout << index << endl;
if (index != -1) {
levels[i]->parkVehicle(&vehicle, VehicleSize::Compact, index, 1);
vehicle2level[&vehicle] = levels[i];
return true;
}
}
return false;
}
bool parkInLargeSpot(Vehicle &vehicle, int num) {
for(int i = 0; i < levels.size(); i++) {
int index = levels[i]->canParkVehicle(&vehicle, VehicleSize::Large, num);
if (index != -1) {
levels[i]->parkVehicle(&vehicle, VehicleSize::Large, index, num);
vehicle2level[&vehicle] = levels[i];
return true;
}
}
return false;
}
// unPark the vehicle
void unParkVehicle(Vehicle &vehicle) {
Level *level = vehicle2level[&vehicle];
if (level) {
level->unParkVehicle(&vehicle);
}
}
};
