Find min and max elements of array

Question

I want to find the min and max elements of an array using for comprehension. Is it possible to do that with one iteration of array to find both min element and max element?

I am looking for a solution without using scala provided array.min or max.

Answer 1

You can get min and max values of an Array[Int] with reduceLeft function.

scala> val a = Array(20, 12, 6, 15, 2, 9) 

a: Array[Int] = Array(20, 12, 6, 15, 2, 9)

scala> a.reduceLeft(_ min _) 

res: Int = 2

scala> a.reduceLeft(_ max _) 

res: Int = 20

See this link for more information and examples of reduceLeft method: http://alvinalexander.com/scala/scala-reduceleft-examples

Answer 2

Here is a concise and readable solution, that avoids the ugly if statements :

def minMax(a: Array[Int]) : (Int, Int) = {   if (a.isEmpty) throw new java.lang.UnsupportedOperationException("array is empty")   a.foldLeft((a(0), a(0)))   { case ((min, max), e) => (math.min(min, e), math.max(max, e))} } 

Explanation : foldLeft is a standard method in Scala on many collections. It allows to pass an accumulator to a callback function that will be called for each element of the array.

Take a look at scaladoc for further details