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Kotlin program to display Armstrong numbers between a range

Kotlin | Armstrong numbers between a range: Here, we are going to learn how to find and display Armstrong numbers between given range in Kotlin programming language? Submitted by IncludeHelp, on April 22, 2020

Kotlin - Display Armstrong numbers between a range

An Armstrong number is a number such that the sum of the n^th power of its digits is equal to the number itself, where n is the number of digits in the number (taken here to mean positive integer).

abcd = a^n + b^n + c^n + d^n

Problem statement

Given two numbers start and end, we have to display the list of Armstrong numbers between start and end.

Example:

Input:
start = 15
end = 700

Output:
[153, 370, 371, 407]

Program to display Armstrong numbers between a range in Kotlin

/**
	* Kotlin Program to check find out ArmStrong number 
	* between given Range(include START and END)
 */

package com.includehelp.basic

import java.util.*

// Function for check Armstrong number
fun findArmStrongNo(number: Long): Boolean {
    var isArmNumber = false
    var result : Long= 0
    var original = number

    //Count No Digits in numbers
    val digits = original.toString().length

    while (original > 0) {
        val r = original % 10
        result +=Math.pow(r.toDouble(), digits.toDouble()).toLong()
        original /= 10
    }

    if (result == number) {
        isArmNumber = true
    }
    return isArmNumber
}


//Main Function, Entry Point of Program
fun main(arg: Array<String>) {
    //Input Stream
    val sc = Scanner(System.`in`)

    //Input Start of Range
    print("Enter Start of Range  : ")
    val start: Long = sc.nextLong()

    //Input End of Range
    print("Enter End of Range  : ")
    val end: Long = sc.nextLong()

    //Declare Mutable List to hold factors
    val list: MutableList<Long> = ArrayList()

    //iterate through loop start to end to find ArmStrong in Range
    for (i in start..end) {
        if (findArmStrongNo(i)) {
            list.add(i)
        }
    }

    println("Armstrong Numbers from $start to $end  : $list")
}

Output

RUN 1:
Enter Start of Range  : 15
Enter End of Range  : 700
Armstrong Numbers from 15 to 700  : [153, 370, 371, 407]
---
RUN 2:
Enter Start of Range  : 99
Enter End of Range  : 999999
Armstrong Numbers from 99 to 999999  : [153, 370, 371, 407, 1634, 8208, 9474, 54748, 92727, 93084, 548834]