Challenge 1: A Generic Constrained Function — Solution

fun <T : Comparable<T>> middle(a: T, b: T, c: T): T {
    return when {
        (a >= b && a <= c) || (a <= b && a >= c) -> a
        (b >= a && b <= c) || (b <= a && b >= c) -> b
        else -> c
    }
}

fun main() {
    println(middle(5, 1, 9))
    println(middle("banana", "apple", "cherry"))
}

/*
Output:
5
banana

Notes:
- <T : Comparable<T>> restricts T to any type that supports comparison
  (>=, <=), which is what makes the "is a between b and c" checks valid
  inside the function body.
- middle(5, 1, 9): 5 sits between 1 and 9, so it's the middle value.
- middle("banana", "apple", "cherry"): alphabetically apple < banana <
  cherry, so "banana" is the middle value.
- The same function works for both Int and String (and any other
  Comparable type) without any changes, because it's generic.
*/