blue-print-solution.md

// P41 (**) A list of Goldbach compositions.
//     Given a range of integers by its lower and upper limit, print a list of
//     all even numbers and their Goldbach composition.
//
//     scala> printGoldbachList(9 to 20)
//     10 = 3 + 7
//     12 = 5 + 7
//     14 = 3 + 11
//     16 = 3 + 13
//     18 = 5 + 13
//     20 = 3 + 17
//
//     In most cases, if an even number is written as the sum of two prime
//     numbers, one of them is very small.  Very rarely, the primes are both
//     bigger than, say, 50.  Try to find out how many such cases there are in
//     the range 2..3000.
//
//     Example (minimum value of 50 for the primes):
//     scala> printGoldbachListLimited(1 to 2000, 50)
//     992 = 73 + 919
//     1382 = 61 + 1321
//     1856 = 67 + 1789
//     1928 = 61 + 1867

object S99Int {
  def printGoldbachList(r: Range) {
    printGoldbachListLimited(r, 0)
  }
  
  def printGoldbachListLimited(r: Range, limit: Int) {
    (r filter { n => n > 2 && n % 2 == 0 } map { n => (n, n.goldbach) }
     filter { _._2._1 >= limit } foreach {
       _ match { case (n, (p1, p2)) => println(n + " = " + p1 + " + " + p2) }
     })
  }
}```