프로그래머스 - 이중우선순위큐

풀이

import java.util.*

/*
 * 2020-11-07
 * https://programmers.co.kr/learn/courses/30/lessons/42628
 */

fun solveDoublePriorityQueue(operations: Array<String>): IntArray {
    val minQueue = PriorityQueue<Int> { n1, n2 -> n1 - n2 }
    val maxQueue = PriorityQueue<Int> { n1, n2 -> n2 - n1 }

    operations.forEach {
        val (arg, numStr) = it.split(" ")
        val num = numStr.toInt()
        if (arg == "I") {
            minQueue.add(num)
            maxQueue.add(num)
        }
        if (arg == "D") {
            if (num == 1) {
                val max = maxQueue.poll()
                minQueue.remove(max)
            }
            if (num == -1) {
                val min = minQueue.poll()
                maxQueue.remove(min)
            }
        }
    }

    return if (minQueue.count() == 0) {
        intArrayOf(0, 0)
    } else {
        intArrayOf(maxQueue.poll(), minQueue.poll())
    }
}

테스트

class HeapTest {
    companion object {
        @JvmStatic
        fun doublePriorityQueueArgs(): Stream<Arguments> = Stream.of(
            Arguments.of(arrayOf("I 16", "D 1"), intArrayOf(0, 0)),
            Arguments.of(arrayOf("I 7", "I 5", "I -5", "D -1"), intArrayOf(7, 5))
        )
    }

    @ParameterizedTest
    @MethodSource("doublePriorityQueueArgs")
    fun testDoublePriorityQueue(operations: Array<String>, expected: IntArray) {
        val result = solveDoublePriorityQueue(operations)
        assertEquals(expected[0], result[0])
        assertEquals(expected[1], result[1])
    }
}