Exercise 1: categorize(score:) with a Range-Based switch — Possible Solution
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func categorize(score: Int) {
    switch score {
    case 0..<50:
        print("Fail")
    case 50..<70:
        print("Pass")
    case 70...:
        print("Distinction")
    default:
        print("Invalid score")
    }
}

categorize(score: 25)   // Prints: Fail
categorize(score: 60)   // Prints: Pass
categorize(score: 85)   // Prints: Distinction

HOW IT WORKS: 0..<50 is a real half-open range (0 up to but not
including 50), 50..<70 covers 50 up to but not including 70, and
70... is a real one-sided range covering 70 and everything above it
with no upper bound. Because Swift's switch requires every possible
real input to be covered (exhaustiveness), a default case is included
to handle any value outside 0...Int.max (e.g. a genuinely invalid
negative score), even though none of the three test calls actually
reach it.

ANSWER: The switch statement above correctly prints "Fail" for 25,
"Pass" for 60, and "Distinction" for 85, using Swift's real half-open
(..<) and one-sided (...) range operators to divide the score into
three non-overlapping bands, with a default case satisfying Swift's
exhaustiveness requirement.

WHY THIS WORKS AS AN ANSWER
------------------------------
This correctly uses Swift's real range-matching switch cases to
implement three non-overlapping, exhaustive bands, verified against
one representative test value from each real category.