A small portion of a toy SkipList with polymorphic find for instructional purposes

SkipList.kt

class SkipList {

  data class Node<Value>(val id: Value, val children: MutableList<Node<Value>> = mutableListOf())

  abstract class Value<T>(val value: T) {
    abstract fun distance(other: T): Int
  }

  class IntValue(id: Int) : Value<Int>(id) {
    override fun distance(other: Int): Int = kotlin.math.abs(this.value - other)
  }

  fun <V : Value<T>, T> find(findMe: V, node: Node<V>): Node<V>? {
    // If this node is the one we are looking for, return it
    if (findMe.value == node.id.value) return node

    // If this node has no children, value is not present
    if (node.children.isEmpty()) return null

    // Traverse the children to see if the target is present 
    node.children.forEach {
      if (it.id.value == findMe.value) return it
    }

    // Find the best child to traverse based on distance
    val bestChild = node.children.minByOrNull { child ->
      findMe.distance(child.id.value)
    } ?: return null

    // Recursively call `find` on the best child
    return find(findMe, bestChild)
  }
	
}