Enum usage (VehicleType, SpotType) in LLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an enum for vehicle types.

LLD

enum VehicleType { [1] }

Drag options to blanks, or click blank then click option'

Acar, bike, truck

B1, 2, 3

CCAR, BIKE, TRUCK

DVehicle, Spot, Type

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or numeric values instead of identifiers.

The enum values should be uppercase identifiers separated by commas.

2fill in blank

medium

Complete the code to declare an enum for parking spot types.

LLD

enum SpotType { [1] }

Drag options to blanks, or click blank then click option'

ASpot, Type, Vehicle

Bcompact, large, handicapped

C1, 2, 3

DCOMPACT, LARGE, HANDICAPPED

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or numbers instead of identifiers.

Enum values should be uppercase and represent spot categories.

3fill in blank

hard

Fix the error in the enum declaration for VehicleType.

LLD

enum VehicleType { CAR, BIKE, [1] }

Drag options to blanks, or click blank then click option'

ATRUCK

Btruck

C3

DVehicle

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or numeric values in enum.

Enum values must be uppercase identifiers, so TRUCK is correct.

4fill in blank

hard

Fill both blanks to complete the enum and use it in a variable declaration.

LLD

enum SpotType { [1] }
SpotType mySpot = [2];

Drag options to blanks, or click blank then click option'

ACOMPACT, LARGE, HANDICAPPED

BCOMPACT

CSpotType.COMPACT

Dcompact

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning variable without enum prefix or using lowercase values.

The enum must list all spot types, and the variable should be assigned using the enum type prefix.

5fill in blank

hard

Fill all three blanks to declare VehicleType enum, assign a variable, and compare it.

LLD

enum VehicleType { [1] }
VehicleType myVehicle = [2];
if (myVehicle == [3]) {
    // park vehicle
}

Drag options to blanks, or click blank then click option'

ACAR, BIKE, TRUCK

BVehicleType.CAR

Dcar

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or missing enum prefix in assignment or comparison.

Enum declaration uses uppercase values, variable assigned with enum prefix, and comparison uses enum prefix as well.

Practice

1. What is the main purpose of using enum types like VehicleType and SpotType in system design?

easy

A. To group related constant values and prevent invalid inputs

B. To store large amounts of data efficiently

C. To perform complex mathematical calculations

D. To create user interface elements dynamically

Solution

1. Step 1: Understand enum purpose

   Enums group related constant values, making code clearer and safer.

2. Step 2: Identify benefits in system design

   They prevent invalid values by restricting inputs to predefined options.

3. Final Answer:

   To group related constant values and prevent invalid inputs -> Option A

4. Quick Check:

   Enums = group constants + prevent errors [OK]

Hint: Enums group fixed options to avoid mistakes [OK]

Common Mistakes:

• Thinking enums store large data
• Confusing enums with data structures
• Using enums for UI elements

2. Which of the following is the correct syntax to define an enum VehicleType with values CAR, BIKE, and TRUCK?

easy

A. enum VehicleType = [CAR, BIKE, TRUCK]

B. enum VehicleType { CAR, BIKE, TRUCK }

C. VehicleType = enum(CAR, BIKE, TRUCK)

D. enum VehicleType: CAR, BIKE, TRUCK

Solution

1. Step 1: Recall enum declaration syntax

   Standard enum syntax uses curly braces with comma-separated values.

2. Step 2: Match syntax to options

   enum VehicleType { CAR, BIKE, TRUCK } matches the correct syntax: enum VehicleType { CAR, BIKE, TRUCK }.

3. Final Answer:

   enum VehicleType { CAR, BIKE, TRUCK } -> Option B

4. Quick Check:

   Enum syntax = curly braces + commas [OK]

Hint: Enums use braces and commas for values [OK]

Common Mistakes:

• Using equal sign instead of braces
• Using square brackets for enums
• Missing commas between values

3. Given the enum SpotType { COMPACT, LARGE, HANDICAPPED } and a function that assigns spots based on vehicle type, what will be the output of this code snippet?

VehicleType vehicle = VehicleType.CAR;
SpotType spot;
switch(vehicle) {
  case VehicleType.CAR:
    spot = SpotType.COMPACT;
    break;
  case VehicleType.BIKE:
    spot = SpotType.HANDICAPPED;
    break;
  default:
    spot = SpotType.LARGE;
}
print(spot);

medium

A. Error: VehicleType not handled

B. HANDICAPPED

C. COMPACT

D. LARGE

Solution

1. Step 1: Identify vehicle type value

   VehicleType is set to CAR.

2. Step 2: Follow switch-case logic

   For CAR, spot is assigned COMPACT.

3. Final Answer:

   COMPACT -> Option C

4. Quick Check:

   CAR maps to COMPACT spot [OK]

Hint: Match enum cases carefully in switch [OK]

Common Mistakes:

• Confusing BIKE case with CAR
• Assuming default runs for CAR
• Ignoring break statements

4. Consider this enum usage snippet:

enum VehicleType { CAR, BIKE, TRUCK }

void assignSpot(VehicleType v) {
  if (v == VehicleType.CAR) {
    print("Compact Spot");
  } else if (v == VehicleType.BIKE) {
    print("Bike Spot");
  }
}

What is the problem if assignSpot(VehicleType.TRUCK) is called?

medium

A. Prints "Bike Spot" incorrectly

B. Syntax error due to missing TRUCK case

C. Runtime error because TRUCK is invalid

D. No output because TRUCK case is not handled

Solution

1. Step 1: Analyze if-else conditions

   Only CAR and BIKE cases are handled explicitly.

2. Step 2: Consider TRUCK input

   TRUCK does not match any condition, so no print occurs.

3. Final Answer:

   No output because TRUCK case is not handled -> Option D

4. Quick Check:

   Unhandled enum value = no output [OK]

Hint: Always handle all enum values or add default [OK]

Common Mistakes:

• Expecting syntax or runtime error
• Assuming default print happens
• Confusing enum invalidity

5. In a parking system, you have enums VehicleType { CAR, BIKE, TRUCK } and SpotType { COMPACT, LARGE, HANDICAPPED }. You want to assign spots such that:
- Cars use COMPACT spots
- Bikes use HANDICAPPED spots
- Trucks use LARGE spots

Which design approach best ensures no invalid spot assignment happens?

hard

A. Use a mapping dictionary from VehicleType to SpotType and validate assignments

B. Use separate if-else blocks without enums for flexibility

C. Assign spots randomly and check later if valid

D. Use strings instead of enums for vehicle and spot types

Solution

1. Step 1: Understand enum benefits for mapping

   Enums provide fixed sets, so mapping ensures clear, valid assignments.

2. Step 2: Evaluate design options

   Mapping dictionary with enums enforces rules and prevents invalid spots.

3. Final Answer:

   Use a mapping dictionary from VehicleType to SpotType and validate assignments -> Option A

4. Quick Check:

   Mapping enums = safe, clear assignments [OK]

Hint: Map enums directly to enforce valid pairs [OK]

Common Mistakes:

• Using strings loses type safety
• Random assignment causes errors
• If-else without enums is error-prone