Sort By Digit Sum - KOTLIN

// Author : Saurav Kalsoor
// Sort By Digit Sum - KOTLIN

import java.util.*

var sc: Scanner = Scanner(System.`in`)

fun main() {
    val n: Int = sc.nextInt()
    val arr: ArrayList<Int> = java.util.ArrayList<Int>()
    for (i in 0 until n) {
        val input: Int = sc.nextInt()
        arr.add(input)
    }

    val result: ArrayList<Int> = sortByDigits(arr)

    for (i in 0 until n)
        print(result.get(i).toString() + " ")
    println()
}

fun sortByDigits(arr: ArrayList<Int>): ArrayList<Int> {
    Collections.sort(arr, SortBySumOfDigits())
    return arr
}

internal class SortBySumOfDigits : Comparator<Int> {
    override fun compare(a: Int, b: Int): Int {
        val sumA = getSum(a)
        val sumB = getSum(b)
        return if (sumA == sumB) {
            a - b
        } else {
            sumA - sumB
        }
    }

    fun getSum(num: Int): Int {
        var n = num
        var sum = 0
        while (n > 0) {
            sum = sum + n % 10
            n = n / 10
        }
        return sum
    }
}