euler problem 12

p012.scala

import scala.annotation.tailrec

@tailrec
def countDivisors(i: Int, n: Int, count:Int = 0):Int = {
  val end = math.sqrt(n).toInt
  (n % i) match {
    case x if n == 1 => 1
    case x if i >= end && end * end == n => count + 2
    case x if i >= end =>  count
    case 0 => countDivisors(i + 1, n, count + 2)
    case _ => countDivisors(i + 1, n, count)
  }
}

@tailrec
def loop(n:Int, limit:Int, i:Int = 1):Int = {
  countDivisors(1, n) match {
    case x if x > limit => n
    case _ => loop(n + i + 1, limit, i + 1)
  }
}

loop(1, 500) // 76576500