LeetCode #2 Happy Number

happyNumber.kt

fun main(args: Array<String>) {
    println(isHappy(1111111))
}

fun isHappy(n: Int): Boolean {
    val mathed = doTheMath(n)
    println(mathed)
    return mathed == 1
}

fun doTheMath(myNum: Int): Int {
    var mutableParam = myNum
    val digits = ArrayList<Int>()
    while (mutableParam > 0) {
        digits.add(mutableParam % 10)
        mutableParam /= 10
    }

    println(digits)

    val summed = digits.map { it * it }.sum()

    println(summed)

    return if (summed.length() > 1) {
        doTheMath(summed)
    } else {
        summed
    }
}

fun Int.length() = when(this) {
    0 -> 1
    else -> Math.log10(Math.abs(toDouble())).toInt() + 1
}