factor calculator class for a blog post

factorcalculatorclass.kt

class FactorCalculator {
    val sumCache = hashMapOf<Int, Int>()
    val factorCache = hashMapOf<Int, List<Int>>()

    fun sumOfFactors(number: Int) = sumCache.getOrPut(number, {
        factorsOf(number).sum()
    })

    fun isFactor(number: Int, potential: Int) = number % potential == 0

    fun factorsOf(number: Int) = factorCache.getOrPut(number, {
        (1 to number).toList().filter { isFactor(number, it) }
    })
}