Solution of https://www.hackerrank.com/challenges/pairs

PairWithDifference.scala

package hackerrank.pairs

/**
  * Created by vparashar on 27/01/2017.
  */
object PairWithDifference {

  def main(args: Array[String]) {
    val sc = new java.util.Scanner(System.in)
    val n = sc.nextInt()
    val k = sc.nextInt()
    val dummy = "Dummy"
    val map = scala.collection.mutable.HashMap.empty[Int, String]
    for (i <- 0 to n - 1) {
      map += ((sc.nextInt(), dummy))
    }
    val pairs = map.keySet.foldLeft(0)((c, n) => if (map.contains(n + k)) c + 1 else c + 0)
    print(pairs)
  }
}