ShellSort.kt

fun MutableList<Int>.swap(index1: Int, index2: Int) {
    val tmp = this[index1]
    this[index1] = this[index2]
    this[index2] = tmp
}

fun MutableList<Int>.shellSort(): MutableList<Int> {

    var sublistCount = count() / 2

    while (sublistCount > 0) {

        var index = 0
        outer@while (index >= 0 && index < count()) {

            if (index + sublistCount >= count()) break

            if (this[index] > this[index + sublistCount]) {
                swap(index, index + sublistCount)
            }

            if (sublistCount == 1 && index > 0) {
                while (this[index - 1] > this[index] && index - 1 > 0) {
                    swap(index - 1, index)
                    index -= 1
                }
                index++
            } else {
                index++
                continue@outer
            }
        }

        sublistCount /= 2
    }

    return this
}

fun main(args: Array<String>) {
    var mutableListOfInt = mutableListOf(10, 4, 5, 2, 1, 3, 6, 9, 8, 7)

    print(mutableListOfInt.shellSort().toString())
}