Sort By Reversing Digits - KOTLIN

// Author : Saurav Kalsoor
// Sort By Reversing Digits - KOTLIN

import java.util.*

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

fun main() {
    val n: Int = sc.nextInt()
    val arr: ArrayList<Int> = 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>): java.util.ArrayList<Int> {
    Collections.sort(arr, SortByReversingDigits())
    return arr
}

internal class SortByReversingDigits : Comparator<Int> {
    override fun compare(a: Int, b: Int): Int {
        val revA = reverseDigits(a)
        val revB = reverseDigits(b)
        return if (revA == revB) {
            a - b
        } else {
            revA - revB
        }
    }

    fun reverseDigits(num: Int): Int {
        var n = num
        var rev = 0
        while (n > 0) {
            rev = rev * 10
            rev = rev + n % 10
            n = n / 10
        }
        return rev
    }
}