37. sum(Nil) = 0
head + sum(tail)
def sum(list: List[Int]): Int =
if (list.isEmpty) 0
else list.head + sum(list.tail)
def sum(list: List[Int]): Int = list match {
case Nil => 0
case head :: tail => head + sum(tail)
}
38. def sum(list: List[Int]): Int = list match {
case Nil => 0
case head :: tail => head + sum(tail)
}
def sum(list: List[Int]): Int = {
def loop(acc: Int, l: List[Int]): Int = l match {
case Nil => acc
case head :: tail => loop(acc + head, tail)
}
loop(0, list)
}