gistfile1.scala

 def balance(chars: List[Char]): Boolean = {
    val l = '('
    val r = ')'

    def helper(left: Int, right: Int, c: List[Char]): Boolean = {
      if (c.isEmpty) return (left - right) == 0

      if (right > left) false
      else if (c.head == l) helper(left + 1, right, c.tail)
      else if (c.head == r) {
        helper(left, right + 1, c.tail)
      } else {
        helper(left, right, c.tail)
      }
    }
    helper(0,0,chars)
  }