stupid hashmap

gistfile1.scala

import collection.mutable


case class Pair[A, B](key: A, value: B)

class HMap[K, V](numBuckets: Int) {
  val buckets = Seq.fill(numBuckets)(mutable.ListBuffer.empty[Pair[K, V]])

  def get(k: K): Option[V] =
    buckets(k.hashCode % numBuckets).find(_.key == k).map(_.value) 

  def apply(k: K): Option[V] = get(k)

  def put(k: K, v: V): Unit = {
    val pair = Pair(k, v)
    val bucket = buckets(k.hashCode % numBuckets)
    bucket.indexWhere(_.key == k) match {
      case -1 => bucket.append(pair)
      case n => bucket(n) = pair
    }
  }

  def size: Int = buckets.map(_.size).sum

  def keys: Iterable[K] = buckets.flatMap(_.map(_.key))

  def values: Iterable[V] = buckets.flatMap(_.map(_.value))

  def toSeq: Seq[(K, V)] = buckets.flatMap(_.map(p => (p.key, p.value)))

  def numEmptyBuckets: Int = buckets.count(_.isEmpty)

}

val m = new HMap[Int, Int](10)
assert(m.numEmptyBuckets == 10)
Range(1, 20).foreach(i => m.put(i, i * 11))
m.put(3, 333)
assert(m.size == 19)
assert(m.get(9) == Some(99))
assert(m.get(3) == Some(333))
assert(m.get(30) == None)