Problem Statement

Given two sets A and B, compute

( A ∖ B ) ∪ ( B ∖ A ) .

{\displaystyle (A\setminus B)\cup (B\setminus A).}

That is, enumerate the items that are in A or B but not both. This set is called the symmetric difference of A and B. In other words:

( A ∪ B ) ∖ ( A ∩ B )

{\displaystyle (A\cup B)\setminus (A\cap B)}

(the set of items that are in at least one of A or B minus the set of items that are in both A and B). Optionally, give the individual differences (

A ∖ B

{\displaystyle A\setminus B}

and

B ∖ A

{\displaystyle B\setminus A}

) as well.

Let's start with the solution:

let setA : Set<String> = ["John", "Bob", "Mary", "Serena"]
let setB : Set<String> = ["Jim", "Mary", "John", "Bob"]
println(setA.exclusiveOr(setB)) // symmetric difference of A and B
println(setA.subtract(setB)) // elements in A that are not in B