Hackerrank - Modified Kaprekar Numbers

Hackerrank – Problem Statement

A description of the problem can be found on Hackerrank.

Solution

Iterate from p to q and check if actual number Kaprekar number (the addition of 2 parts of squared number is equal to actual number)

I created solution in:

Scala
Java
JavaScript
Ruby

All solutions are also available on my GitHub.

Java

import java.util.*;

public class ModifiedKaprekarNumbers {

    public static void main(String[] args) {
        Scanner stdin = new Scanner(System.in);
        int lower = stdin.nextInt();
        int upper = stdin.nextInt();
        List<Integer> kaprekars = new ArrayList<>();
        for(int i = lower; i <= upper; i++) {
            if(isKaprekar(i)) {
                kaprekars.add(i);
            }
        }
        if(kaprekars.isEmpty()) {
            System.out.println("INVALID RANGE");
        } else {
            for(int k : kaprekars) {
                System.out.print(k + " ");
            }
        }
        stdin.close();
    }

    private static boolean isKaprekar(int num) {
        String square = Long.valueOf((long) Math.pow(num, 2)).toString();
        if(square.length() > 1) {
            long l = Long.parseLong(square.substring(0, square.length() / 2));
            long r = Long.parseLong(square.substring(square.length() / 2));
            return (l + r) == num;
        } else {
            return Long.parseLong(square) == num;
        }
    }
}

import java.util.*;

public class ModifiedKaprekarNumbers {

public static void main(String[] args) {

Scanner stdin = new Scanner(System.in);

int lower = stdin.nextInt();

int upper = stdin.nextInt();

List<Integer> kaprekars = new ArrayList<>();

for(int i = lower; i <= upper; i++) {

if(isKaprekar(i)) {

kaprekars.add(i);

}

if(kaprekars.isEmpty()) {

System.out.println("INVALID RANGE");

} else {

for(int k : kaprekars) {

System.out.print(k + " ");

}

stdin.close();

}

private static boolean isKaprekar(int num) {

String square = Long.valueOf((long) Math.pow(num, 2)).toString();

if(square.length() > 1) {

long l = Long.parseLong(square.substring(0, square.length() / 2));

long r = Long.parseLong(square.substring(square.length() / 2));

return (l + r) == num;

} else {

return Long.parseLong(square) == num;

}

JavaScript

'use strict';

const processData = input => {
    const lines = input.split('\n').map(i => parseInt(i));
    const lower = lines[0];
    const upper = lines[1];
    const kaprekarNums = [];
    for(let i = lower; i <= upper; i++) {
        if(isKaprekar(i)) {
            kaprekarNums.push(i);
        }
    }
    if(kaprekarNums.length > 0) {
        console.log(kaprekarNums.join(" "));
    } else {
        console.log("INVALID RANGE");
    }
};

const isKaprekar = (num) => {
    const square = parseInt(Math.pow(num, 2)).toString();
    if(square.length > 1) {
        const l = parseInt(square.substring(0, square.length / 2));
        const r = parseInt(square.substring(square.length / 2));
        return (l + r) === num;
    } else {
        return parseInt(square) === num;
    }
}

process.stdin.resume();
process.stdin.setEncoding("ascii");

var _input = "";
process.stdin.on("data", input => _input += input);
process.stdin.on("end", () => processData(_input));

'use strict';

const processData = input => {

const lines = input.split('\n').map(i => parseInt(i));

const lower = lines[0];

const upper = lines[1];

const kaprekarNums = [];

for(let i = lower; i <= upper; i++) {

if(isKaprekar(i)) {

kaprekarNums.push(i);

}

if(kaprekarNums.length > 0) {

console.log(kaprekarNums.join(" "));

} else {

console.log("INVALID RANGE");

}

};

const isKaprekar = (num) => {

const square = parseInt(Math.pow(num, 2)).toString();

if(square.length > 1) {

const l = parseInt(square.substring(0, square.length / 2));

const r = parseInt(square.substring(square.length / 2));

return (l + r) === num;

} else {

return parseInt(square) === num;

}

process.stdin.resume();

process.stdin.setEncoding("ascii");

var _input = "";

process.stdin.on("data", input => _input += input);

process.stdin.on("end", () => processData(_input));

Scala

import scala.io.Source

object ModifiedKaprekarNumbers extends App {
  val lines = Source.stdin.getLines().map(_.toInt).toList
  val lower = lines(0)
  val upper = lines(1)
  val kaprekarNums = (lower to upper).filter(isKaprekar)
  val output = if(!kaprekarNums.isEmpty) kaprekarNums.mkString(" ") else "INVALID RANGE"

  def isKaprekar(num: Int): Boolean = {
    val square = Math.pow(num, 2).toInt.toString
    if(square.length > 1) {
      val parts = square.splitAt(square.length / 2)
      val l = parts._1.toInt
      val r = parts._2.toInt
      return (l + r) == num
    } else {
      return square.toInt == num
    }
  }
}

import scala.io.Source

object ModifiedKaprekarNumbers extends App {

val lines = Source.stdin.getLines().map(_.toInt).toList

val lower = lines(0)

val upper = lines(1)

val kaprekarNums = (lower to upper).filter(isKaprekar)

val output = if(!kaprekarNums.isEmpty) kaprekarNums.mkString(" ") else "INVALID RANGE"

def isKaprekar(num: Int): Boolean = {

val square = Math.pow(num, 2).toInt.toString

if(square.length > 1) {

val parts = square.splitAt(square.length / 2)

val l = parts._1.toInt

val r = parts._2.toInt

return (l + r) == num

} else {

return square.toInt == num

}

Ruby

def is_kaprekar(num)
  square = (num ** 2).to_s
  if(square.size > 0)
    l = square.slice(0, (square.size / 2).to_i).to_i
    r = square.slice((square.size / 2).to_i, (square.size)).to_i
    return (l + r) == num
  else
    return square.to_i == num
  end
end

lower = gets.to_i
upper = gets.to_i
kaprekars = []
for i in lower..upper
  kaprekars << i if(is_kaprekar(i))
end

if(kaprekars.size > 0)
  puts kaprekars.join(" ")
else
  puts "INVALID RANGE"
end

def is_kaprekar(num)

square = (num ** 2).to_s

if(square.size > 0)

l = square.slice(0, (square.size / 2).to_i).to_i

r = square.slice((square.size / 2).to_i, (square.size)).to_i

return (l + r) == num

else

return square.to_i == num

end

lower = gets.to_i

upper = gets.to_i

kaprekars = []

for i in lower..upper

kaprekars << i if(is_kaprekar(i))

end

if(kaprekars.size > 0)

puts kaprekars.join(" ")

else

puts "INVALID RANGE"

end

Pavol Pidanič

I can count to 1023 with 10 fingers

Hackerrank – Modified Kaprekar Numbers

Hackerrank – Problem Statement

Solution

Java

JavaScript

Scala

Ruby

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