Happy Numbers

HappyNumbers.groovy

// See: https://en.wikipedia.org/wiki/Happy_number

(1 .. 100).each { n ->
   println "$n:"
   def sums = []

   while (true) {
      def squares = (n as String).collect { (it as int) ** 2 }
      n = squares.sum()
      println "   $squares => $n" + (n == 1 ? " (happy)" : "")

      // Could check that n is in [ 0, 1, 4, 16, 20, 37, 42, 58, 89, or 145 ].
      if ((n == 1) || sums.contains(n)) {
         break
      }

      sums << n
   }
}