find the kth largest number in a list in swift

main.swift
func kthLargestNumber(_ arr: [Int], _ k: Int) -> Int? {
    guard k > 0 && k <= arr.count else {
        return nil // invalid input
    }
    let sortedArr = arr.sorted(by: >) // sort array in descending order
    return sortedArr[k - 1] // return kth largest number
}
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main.swift
let arr = [3, 2, 1, 5, 4]
if let kthLargest = kthLargestNumber(arr, 3) {
    print("The 3rd largest number in \(arr) is \(kthLargest)") // prints "The 3rd largest number in [3, 2, 1, 5, 4] is 3"
} else {
    print("Invalid input") // prints "Invalid input"
}
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