Exponentiate Algorithm.swift

/* Two exponentiate algorithms, the first one it's better than second. */

func exponentiate(number : Int, exponent : Int) -> Int {
    var n = number, e = exponent, r = 1, v = 0
    func descriptionVar() -> String { return "Loop v :\(v), n =\(n), e = \(e), r = \(r)" }
    while (e > 0) {
        if e%2 != 0 { r = r*n }
        e /= 2
        n *= n
        v++
        descriptionVar()
    }
    return r
}

exponentiate(2, 9) -> 4 loops
//Loop v :1, n =4, e = 4, r = 2
//Loop v :2, n =16, e = 2, r = 2
//Loop v :3, n =256, e = 1, r = 2
//Loop v :4, n =65536, e = 0, r = 512

func exponentiate2(number : Int, exponent : Int) -> Int {
    var n = exponent, r = 1
    while (n > 0) {
        r *= number  ;
        n--;
    }
    return r
}
exponentiate2(2, 9) -> 9 Loops