Iterator Recursion

MyIterator.kt

// написать имплементацию интерфейса Iterator<T>, где Т может быть либо Int, либо Iterator<T>

interface MyIterator<T> {
    fun hasNext(): Boolean
    fun next(): T
}

class IntRecursionImpl(
    items: List<Any>
): MyIterator<Int> {

    val items = items.reversed().toMutableList()
    var nextItem: Int? = null

    override fun hasNext(): Boolean {
        val lastItem = items.lastOrNull() ?: return false
        if (lastItem is Int) {
            nextItem = lastItem
            items.removeLast()
            return true
        }
        lastItem as MyIterator<*> 
        return if (lastItem.hasNext()) {
            val next = lastItem.next()
            if (next is MyIterator<*>) {
                items.add(next)
                hasNext()
            } else {
                nextItem = next as Int
                true
            }
        } else {
            items.removeLast()
            hasNext()
        }
    }

    override fun next(): Int {
        if (nextItem == null) {
            hasNext()
        }
        return nextItem ?: throw IllegalStateException()
    }

}