Happy Numbers

isHappy.scala

def isHappy(num: Int): Boolean = isHappy(num, Set())
def isHappy(num: Int, seen: Set[Int]): Boolean = {
  def inner(sum: Int, num: Int): Int = {
    val digit = num % 10
    val squared = math.pow(digit, 2).toInt
    if (num < 10) sum + squared
    else inner(sum + squared, (num - digit) / 10)
  }
  val ssd = inner(0, num)
  if (seen.contains(ssd)) false
  else if (ssd == 1) true
  else isHappy(ssd, seen + ssd)
}

val happys = Set(1, 7, 10, 13, 19, 23, 28, 31, 32, 44, 49, 68, 70, 79, 82, 86, 91, 94, 97, 100, 103, 109, 129, 130, 
  133, 139, 167, 176, 188, 190, 192, 193, 203, 208, 219, 226, 230, 236, 239, 262, 263, 280, 291, 293, 301, 302, 310, 
  313, 319, 320, 326, 329, 331, 338, 356, 362, 365, 367, 368, 376, 379, 383, 386, 391, 392, 397, 404, 409,
  440, 446, 464, 469, 478, 487, 490, 496)
val truths = happys.map(isHappy)
println(truths)

val falsehoods = ((2 to 500).toSet -- happys).map(isHappy)
println(falsehoods)