is it possible to write functional version for below imperative code in scala

Question

I wrote sum code in scala to find the majority element(the element which appears more than n/2 times where 'n' is the no.of elements in an array.I want to know where there is functional / scala native style of version(which includes match cases and transformations like "map/"flatmap" etc..) for the below imperative style of scala code which includes looping. The code which i used in:

object MajorityElement{

 def printMajority(arr:Array[Int]) ={
 var cand:Int=findCandidate(arr);
  if(isMajority(arr,cand))
    println(cand);
  else
    println("No Majority Element");
 }

def isMajority(arr:Array[Int],Cand:Int):Boolean ={
  var count=0;
   for(i <- 0 until arr.length){
    if(arr(i)== Cand)
      count+=1;
    }
 if (count > arr.size/2)
   return true;
 else false
 }

def findCandidate(arr:Array[Int]):Int ={
 val s = arr.size
 var majIndex:Int = 0;
 var count = 1;
  for(i <- 0 until arr.length){

     if(arr(majIndex) == arr(i))
       count+=1;
     else
       count-=1;
     if(count==0)
       {
       majIndex = i;
       count =1
        }
    }
 return arr(majIndex);
  }
}

please let me know, whether it is possible to write/ convert imperative style to functional version in scala(which uses match cases) for any scenario.

Answer 1

Threr is no Native Scala Style, but code can be Functional Style(value oriented)

(No var, No Side-Effect, Pure Function)

object MajorityElement {

  case class Candidate(idx: Int, count: Int)

  def solve(arr: Array[Int]): Option[Int] = {
    val candidate = findCandidate(arr)

    if (isMajority(arr, candidate)) Option(arr(candidate.idx))
    else None
  }

  def isMajority(arr: Array[Int], candidate: Candidate) =
    arr.count(_ == arr(candidate.idx)) > arr.size / 2

  def findCandidate(arr: Array[Int]): Candidate =
    arr.indices.foldLeft(Candidate(0, 1)) { (acc, idx) =>
      val newAcc =
        if (arr(acc.idx) == arr(idx)) acc.copy(count = acc.count + 1)
        else acc.copy(count = acc.count - 1)

      if (newAcc.count == 0) Candidate(idx, 1)
      else newAcc
    }
}

val arr = Array(1, 1, 1, 2, 3, 4, 1)
val ret = MajorityElement.solve(arr)

ret match {
  case Some(n) => println(s"Found Majority Element: $n")
  case None => println("No Majority Element")
}