检查列表中枚举的组合(Kotlin)

fun <T> combine(list: List<T>, length: Int): List<List<T>> {
    if (length == 1) {
        return list.map { listOf(it) }
    }
    if (list.isEmpty()) {
        return emptyList()
    }
    val result = mutableListOf<List<T>>()
    val sublist = list.subList(1, list.size)
    combine(sublist, length - 1).forEach { subResult ->
        result.add(listOf(list[0]) + subResult)
    }
    result.addAll(combine(sublist, length))
    return result
}

fun main() {
    val list = listOf(1, 2, 3, 4)
    val combinations = combine(list, 2)
    combinations.forEach { combination ->
        println(combination)
    }
}