1281. Subtract the Product and Sum of Digits of an Integer

leetCode2

func subtractProductAndSum(_ n: Int) -> Int {
    var givenNum = n
    var num:[Int] = []
    
    if n >= 1 && n <= 100000 {
    repeat {
        let digit = givenNum%10
        givenNum /= 10
        num.append(digit)
    } while (givenNum != 0)
    
    let product = num.map({$0}).reduce(1, *)
    let sum = num.map({$0}).reduce(0, +)
    return product - sum
    }
    return 0
}