Given two strings, write a method to decide if one is a permutation of the other.

AnagramString.scala

import scala.annotation.tailrec

/**
  * given two strings, write a method to decide if one is a permutation of the other.
  * Created by Arun Sethia on 7/5/18.
  */
trait AnagramString {

  final val ASCII_CHAR_LEN: Int = 128

  /**
    * check given two strings are permutation of the other.
    * @param input1
    * @param input2
    * @return
    */
  def isAnagramString(input1: String, input2: String) = {
    val arrayOfCount: Array[Int] = Array.ofDim[Int](ASCII_CHAR_LEN)
    val i = input1.length - 1
    val j = input2.length - 1
    if (i != j) false
    else {
      for (c <- 0 to i) {
        arrayOfCount(input1(c).toInt) = arrayOfCount(input1(c).toInt) + 1
        arrayOfCount(input2(c).toInt) = arrayOfCount(input2(c).toInt) - 1
      }
      checkAnagram(arrayOfCount, 0, true)
    }
  }

  @tailrec
  private def checkAnagram(anagramFlag: Array[Int], count: Int, returnFlag: Boolean): Boolean = {
    if (anagramFlag.length == 0 || !returnFlag) returnFlag
    else if (count == anagramFlag.length) returnFlag
    else checkAnagram(anagramFlag, count + 1, anagramFlag(count) == 0)
  }
}