What is the easiest and most efficient way to make a min heap in Scala?

Question

val maxHeap = scala.collection.mutable.PriorityQueue[Int] //Gives MaxHeap

What is the most concise and efficient way to use Ordering to turn a PriorityQueue into a minHeap?

Answer 1

You'll have to define your own Ordering :

scala> object MinOrder extends Ordering[Int] {
         def compare(x:Int, y:Int) = y compare x
       }
defined object MinOrder

Then use that when creating the heap :

scala> val minHeap = scala.collection.mutable.PriorityQueue.empty(MinOrder)
minHeap: scala.collection.mutable.PriorityQueue[Int] = PriorityQueue()

scala> minHeap.ord
res1: Ordering[Int] = MinOrder$@158ac84e