Set Operations

// Two sets for comparison
let setA: Set = [1, 2, 3, 4, 5]
let setB: Set = [4, 5, 6, 7, 8]

// UNION - All elements from both sets
let union = setA.union(setB)
print("Union: \(union)")
// {1, 2, 3, 4, 5, 6, 7, 8}

// INTERSECTION - Only common elements
let intersection = setA.intersection(setB)
print("Intersection: \(intersection)")
// {4, 5}

// DIFFERENCE - Elements in A but not in B
let difference = setA.subtracting(setB)
print("A - B: \(difference)")
// {1, 2, 3}

// SYMMETRIC DIFFERENCE - Elements in either, not both
let symmetricDiff = setA.symmetricDifference(setB)
print("Symmetric: \(symmetricDiff)")
// {1, 2, 3, 6, 7, 8}

// Real-world example: Students in clubs
let mathClub: Set = ["Alice", "Bob", "Charlie", "Diana"]
let scienceClub: Set = ["Bob", "Diana", "Eve", "Frank"]

// Students in both clubs
let bothClubs = mathClub.intersection(scienceClub)
print("Both clubs: \(bothClubs)")
// ["Bob", "Diana"]

// Students in at least one club
let anyClub = mathClub.union(scienceClub)
print("Any club: \(anyClub)")

// Only math, not science
let onlyMath = mathClub.subtracting(scienceClub)
print("Only math: \(onlyMath)")
// ["Alice", "Charlie"]

// Subset and superset checking
let smallSet: Set = [1, 2]
let bigSet: Set = [1, 2, 3, 4, 5]

print(smallSet.isSubset(of: bigSet))     // true
print(bigSet.isSuperset(of: smallSet))   // true
print(smallSet.isDisjoint(with: setB))   // true (no common)

// Comparing sets
let setC: Set = [1, 2, 3]
let setD: Set = [3, 2, 1]
print(setC == setD)  // true (order doesn't matter!)

// In-place operations
var mySet: Set = [1, 2, 3]
mySet.formUnion([4, 5])        // Modifies mySet
mySet.formIntersection([2, 3, 4])  // Keeps only common
print(mySet)  // {2, 3, 4}