Car and Engine in Kotlin

You build two classes, Engine and Car. A car has an engine and passes work on to it.

Implement:

• Engine(horsepower) makes an engine with that power.
• The engine's start() returns "Engine with H hp started", with its power as H.
• Car(name, engine) makes a car that has this engine.
• The car's start() returns its name and ": " before the engine's start() text.
• swapEngine(engine) puts a new engine in the car.
• horsepower() returns the power of the car's engine.

The class headers are given. They already declare the fields. engine is a var, so a swap can replace it.

Each test makes some cars and calls their methods. Every start and horsepower result is printed on its own line.

Example 1:

Input:
    car = Car("Rocket", Engine(150))
    car.start()
    car.horsepower()
Output:
Rocket: Engine with 150 hp started
150
Explanation: Rocket's engine has 150 hp.
The car puts "Rocket: " before the engine's text.

Example 2:

Input:
    car = Car("Bolt", Engine(90))
    car.start()
    car.horsepower()
    car.swapEngine(Engine(300))
    car.start()
    car.horsepower()
Output:
Bolt: Engine with 90 hp started
90
Bolt: Engine with 300 hp started
300
Explanation: After the swap, Bolt has the 300 hp engine.
Its name stays the same.

Example 3:

Input:
    Engine(7).start()
    car = Car("Ant", Engine(1))
    car.swapEngine(Engine(1000))
    car.horsepower()
Output:
Engine with 7 hp started
1000
Explanation: An engine can start on its own.
Its text has no car name.
Ant's first engine is replaced before any call.

Constraints:

• Each power is a whole number from 1 to 1,000.
• A name is one word of 1 to 10 letters.
• The cars in a test have different names.
• At most 5 cars and 100 calls per test.