Question

How to find K most frequent elements in an unsorted array with Scala

Answer 1

import scala.collection.mutable

def printKMostFrequentNumbers(arr: Array[Int], K: Int): Unit = {
  val mp = mutable.Map[Int, Int]()
  
  for (num <- arr) {
    mp(num) = mp.getOrElse(num, 0) + 1
  }
  
  val sortedMap = mp.toSeq.sortBy(-_._2)
  
  for (i <- 0 until K) {
    println(sortedMap(i)._1)
  }
}

val arr = Array(4, 5, 19, 50, 5, 19, 5, 8, 19, 3, 3, 6, 3, 27, 19, 3, 3)
val K = 2

printKMostFrequentNumbers(arr, K)

 
 
 
/*
run:
   
3
19
 
*/

 

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