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Published at Aug 23 2019
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Instructions

Test suite

Solution

Convert a number to a string, the contents of which depend on the number's factors.

- If the number has 3 as a factor, output 'Pling'.
- If the number has 5 as a factor, output 'Plang'.
- If the number has 7 as a factor, output 'Plong'.
- If the number does not have 3, 5, or 7 as a factor, just pass the number's digits straight through.

- 28's factors are 1, 2, 4,
**7**, 14, 28.- In raindrop-speak, this would be a simple "Plong".

- 30's factors are 1, 2,
**3**,**5**, 6, 10, 15, 30.- In raindrop-speak, this would be a "PlingPlang".

- 34 has four factors: 1, 2, 17, and 34.
- In raindrop-speak, this would be "34".

The Scala exercises assume an SBT project scheme. The exercise solution source should be placed within the exercise directory/src/main/scala. The exercise unit tests can be found within the exercise directory/src/test/scala.

To run the tests simply run the command `sbt test`

in the exercise directory.

For more detailed info about the Scala track see the help page.

A variation on a famous interview question intended to weed out potential candidates. http://jumpstartlab.com

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

```
import org.scalatest.{Matchers, FunSuite}
/** @version 1.1.0 */
class RaindropsTest extends FunSuite with Matchers {
test("the sound for 1 is 1") {
Raindrops.convert(1) should be ("1")
}
test("the sound for 3 is Pling") {
pending
Raindrops.convert(3) should be ("Pling")
}
test("the sound for 5 is Plang") {
pending
Raindrops.convert(5) should be ("Plang")
}
test("the sound for 7 is Plong") {
pending
Raindrops.convert(7) should be ("Plong")
}
test("the sound for 6 is Pling as it has a factor 3") {
pending
Raindrops.convert(6) should be ("Pling")
}
test("2 to the power 3 does not make a raindrop sound as 3 is the exponent not the base") {
pending
Raindrops.convert(8) should be ("8")
}
test("the sound for 9 is Pling as it has a factor 3") {
pending
Raindrops.convert(9) should be ("Pling")
}
test("the sound for 10 is Plang as it has a factor 5") {
pending
Raindrops.convert(10) should be ("Plang")
}
test("the sound for 14 is Plong as it has a factor of 7") {
pending
Raindrops.convert(14) should be ("Plong")
}
test("the sound for 15 is PlingPlang as it has factors 3 and 5") {
pending
Raindrops.convert(15) should be ("PlingPlang")
}
test("the sound for 21 is PlingPlong as it has factors 3 and 7") {
pending
Raindrops.convert(21) should be ("PlingPlong")
}
test("the sound for 25 is Plang as it has a factor 5") {
pending
Raindrops.convert(25) should be ("Plang")
}
test("the sound for 27 is Pling as it has a factor 3") {
pending
Raindrops.convert(27) should be ("Pling")
}
test("the sound for 35 is PlangPlong as it has factors 5 and 7") {
pending
Raindrops.convert(35) should be ("PlangPlong")
}
test("the sound for 49 is Plong as it has a factor 7") {
pending
Raindrops.convert(49) should be ("Plong")
}
test("the sound for 52 is 52") {
pending
Raindrops.convert(52) should be ("52")
}
test("the sound for 105 is PlingPlangPlong as it has factors 3, 5 and 7") {
pending
Raindrops.convert(105) should be ("PlingPlangPlong")
}
test("the sound for 3125 is Plang as it has a factor 5") {
pending
Raindrops.convert(3125) should be ("Plang")
}
}
```

```
object Raindrops {
val factors = Map(
3 -> "Pling",
5 -> "Plang",
7 -> "Plong"
)
def convert(n: Int): String = factors.filterKeys(n % _ == 0).values match {
case ls if ls.isEmpty => n toString
case ls => ls mkString
}
}
```

A huge amount can be learned from reading other peopleâ€™s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

- What compromises have been made?
- Are there new concepts here that you could read more about to improve your understanding?

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