import io.fsq.common.scala.Lists._
import com.foursquare.common.random.RandomUtils.chooseKItems

val list = {0 until 10000}.toList
val n = 50

def time[R](block: => R): R = {
    val t0 = System.nanoTime()
    val result = block
    val t1 = System.nanoTime()
    println("Elapsed time: " + (t1 - t0) + "ns")
    result
}

// NOTE(stpyang): this takes about 1.6 seconds
time (for {
  i <- 0 to 10000
} yield {
  list.sample(n)
}).flatten.groupBy(identity).mapValues(_.size).toSeq.sortBy(_._1)

// NOTE(stpyang): this takes about 10 seconds
time (for {
  i <- 0 to 10000
} yield {
  chooseKItems(list, n)
}).flatten.groupBy(identity).mapValues(_.size).toSeq.sortBy(_._1)