Find the max-diff value in a List with the difference is from the values on the right vs. the value on the left in the List

	//1 - Int
	def maxIntDiff(list: List[Int]): Int =
	@tailrec
	def findMaxDiff(max: Int, diff: Int, as: List[Int]): Int = as match
	case Nil => diff
	case h :: t if h > max => findMaxDiff(h, diff, t)
	case h :: t => findMaxDiff(max, Math.max(diff, max - h), t)
	val rev = list.reverse
	findMaxDiff(Int.MinValue, rev.head, rev.tail)
	//2 - Generic way
	def maxDiff[T: Ordering : Numeric](list: List[T], min: T): T =
	@tailrec
	def findMaxDiff(max: T, diff: T, as: List[T]): T = as match
	case Nil => diff
	case h :: t if Ordering[T].compare(h, max) > 0 => findMaxDiff(h, diff, t)
	case h :: t => findMaxDiff(max, Numeric[T].max(diff, Numeric[T].minus(max, h)), t)
	val rev = list.reverse
	findMaxDiff(min, rev.head, rev.tail)
	//3 - with Max/Min Pair
	def maxDiffInfo[T: Ordering: Numeric](list: List[T], min: T): (T, (T, T)) =
	@tailrec
	def findMaxDiff(max: T, diff: T, as: List[T], pair: (T, T)): (T, (T, T)) = as match
	case Nil => (diff, pair)
	case h::t if Ordering[T].compare(h, max) > 0 => findMaxDiff(h, diff, t, pair)
	case h::t =>
	val nMaxDiff = Numeric[T].max(diff, Numeric[T].minus(max, h))
	findMaxDiff(max, nMaxDiff, t, if Numeric[T].compare(nMaxDiff, diff) != 0 then (h, max) else pair)
	val rev = list.reverse
	findMaxDiff(min, rev.head, rev.tail, (min, min))

view raw find_max_diff.scala hosted with ❤ by GitHub