package leetcode

import kotlin.collections.set

fun main() {
    val nums1 = intArrayOf(1, 2, 2, 1)
    val nums2 = intArrayOf(2, 2)
    println(intersect(nums1, nums2).joinToString())
}

fun intersect(nums1: IntArray, nums2: IntArray): MutableList<Int> {
    val outputMap = hashMapOf<Int, Int>()
    val outputList = mutableListOf<Int>()

    for (i in nums1.indices) {
        if (nums1[i] in outputMap) {
            outputMap[nums1[i]]++
        } else {
            outputMap[nums1[i]] = 1
        }
    }

    for (i in nums2.indices) {
        if (nums2[i] in outputMap && outputMap[nums2[i]] > 1) {
            outputList.add(nums2[i])
            outputMap[nums1[i]]--
        }
    }

    return outputList
}

outputMap[nums1[i]]++

No set method providing array access

for (num1 in nums1) {
    outputMap[num1] = outputMap.getOrElse(num1) { 0 } + 1
}

for (num2 in nums2) {
        outputMap[num2]?.let {
            if (it > 1) {
                outputList.add(num2)
                outputMap[num2] = it - 1
            }
        }
    }

nums2[i] in outputMap && outputMap[nums2[i]] > 1

containsKey.

val nums1 = intArrayOf(1, 2, 2, 1)
val nums2 = intArrayOf(2, 2)

val setOfFirstArray =
        nums1.mapTo(hashSetOf()) { it }

 val intersection =
        nums2.filterTo(hashSetOf()) { n2 -> setOfFirstArray.contains(n2) }

349. Intersection of Two Arrays I

350. Intersection of Two Arrays II