How to find the largest element in a list of integers recursively?

Question

I\'m trying to write a function which will recursively find the largest element in a list of integers. I know how to do this in Java, but can\'t understand how to do this at Sca

Answer 1

I used just head() and tail()

def max(xs: List[Int]): Int = {
    if (xs.isEmpty) throw new NoSuchElementException
    else maxRecursive(xs.tail, xs.head) 
  }
  
  def maxRecursive(xs: List[Int], largest: Int): Int = {
    if (!xs.isEmpty) {
      if (xs.head > largest) maxRecursive(xs.tail, xs.head)
      else maxRecursive(xs.tail, largest)
    } else {
      largest
    }
  }

Here is tests for this logic:

test("max of a few numbers") {
    assert(max(List(3, 7, 2, 1, 10)) === 10)
    assert(max(List(3, -7, 2, -1, -10)) === 3)
    assert(max(List(-3, -7, -2, -5, -10)) === -2)
  }