Random numbers adding up to a sum

random.swift

import Foundation

func randomNumbers(_ count: Int, totalling sum: Int) -> [Int] {
    let randomOffsets = (0 ..< count - 1).map { _ in Int.random(in: 1 ..< sum) }

    let range = ([0] + randomOffsets + [sum]).sorted()

    var values: [Int] = []

    for i in 0 ... count - 1 {
        values.append(range[i + 1] - range[i])
    }

    return values
}