kth_largest_element.kt

fun main(args: Array<String>) {

    val k = 3

    // k smallest element
    
    // by default a PriorityQueue makes a min heap
    val priorityQueue: PriorityQueue<Int> = PriorityQueue<Int>()

    priorityQueue.add(20)
    priorityQueue.add(4)
    priorityQueue.add(1)
    priorityQueue.add(35)
    priorityQueue.add(66)
    priorityQueue.add(12)

    for(i in 1 until k+1){
        val smallest = priorityQueue.peek()
        priorityQueue.poll()
        if(i == k){
            println("Kth smallest: " + smallest)
        }
    }

    
    // k largest element

    // by default a PriorityQueue makes a min heap,
    // reverse the order to make it a max heap

    val priorityQueueReverse: PriorityQueue<Int> =
            PriorityQueue<Int>(Collections.reverseOrder())

    priorityQueueReverse.add(20)
    priorityQueueReverse.add(4)
    priorityQueueReverse.add(1)
    priorityQueueReverse.add(35)
    priorityQueueReverse.add(66)
    priorityQueueReverse.add(12)

    for(i in 1 until k+1){
        val largest = priorityQueueReverse.peek()
        priorityQueueReverse.poll()
        if(i == k){
            println("Kth largest: " + largest)
        }
    }
}