Merge Sort Algorithm using kotlin

MergeSortKT.kt

fun main() {
    val arr = arrayOf(9, 3, 6, 7, 3, 2, 1, 5, 4, 7, 5)
    mergeSort(arr)
    println(arr.contentToString())
}

fun mergeSort(inputArray: Array<Int>) {
    val inputLength = inputArray.size
    if (inputLength < 2) return

    val midIndex = inputLength / 2 // 11 => 5 , 6
    val leftHalf = Array(midIndex) { it }
    val rightHalf = Array(inputLength - midIndex) { it } // 11 - 5 = 6

    leftHalf.forEachIndexed { index, _ ->
        leftHalf[index] = inputArray[index]
    }

    rightHalf.forEachIndexed { index, _ ->
        rightHalf[index] = inputArray[index + midIndex]
    }

    mergeSort(leftHalf)
    mergeSort(rightHalf)

    merge(inputArray, leftHalf, rightHalf)
}

fun merge(inputArray: Array<Int>, leftHalf: Array<Int>, rightHalf: Array<Int>) {
    val leftSize = leftHalf.size
    val rightSize = rightHalf.size
    var i = 0
    var j = 0
    var k = 0

    while (i < leftSize && j < rightSize) {
        if (leftHalf[i] < rightHalf[i]) {
            inputArray[k] = leftHalf[i]
            i++
        } else {
            inputArray[k] = rightHalf[j]
            j++
        }
        k++
    }


    while (i < leftSize) {
        inputArray[k] = leftHalf[i]
        i++
        k++
    }

    while (j < rightSize) {
        inputArray[k] = rightHalf[j]
        j++
        k++
    }

}