NumberConverter.kt

package converter

import java.math.BigInteger

class NumberConverter(
    private val sourceBase: BigInteger,
    private val targetBase: BigInteger
) {

    private fun convertFromDecimal(decimalNumber: BigInteger): String {
        return decimalNumber.toString(targetBase.toInt());
    }

    /**
     * This function converts the input string to decimal number
     * system
     */
    private fun convertToDecimal(numberInput: String): BigInteger {
        return numberInput.toBigInteger(sourceBase.toInt());
    }

    fun convert(input: String): String {
        val decimalNumber = convertToDecimal(input)
        return convertFromDecimal(decimalNumber)
    }
}