How to pass the Fizz Buzz test

Swift version: 5.1

Paul Hudson @twostraws May 28th 2019

The Fizz Buzz test is a simple coding test used in some coding interviews. It’s not designed to be hard, in fact quite the opposite – it’s designed to be easy enough that most folks can solve it without feeling too pressured.

To pass the test you must write a function that accepts an integer and returns a string. Which string to return depends on the input number:

If the integer is evenly divisible by three, it should return “Fizz”.
If the integer is evenly divisible by five, it should return “Buzz”.
If the integer is evenly divisible by three and five, it should return “Fizz Buzz”.
Otherwise it should return the string form of the input number.

There are lots of ways this can be solved in Swift, but I think one of the most interesting is to use tuples like this:

func fizzbuzz(number: Int) -> String {
    switch (number % 3 == 0, number % 5 == 0) {
    case (true, false):
        return "Fizz"
    case (false, true):
        return "Buzz"
    case (true, true):
        return "FizzBuzz"
    case (false, false):
        return String(number)
    }
}

print(fizzbuzz(number: 15))

This approach breaks down a large input space – any number – into simple combinations of true and false, and we then use tuple pattern matching in the case statements to select the correct output.