object stringSession {
  println("Welcome to the Scala worksheet")       //> Welcome to the Scala worksheet

  def isPal(word: String): Boolean = {
    return (word == word.reverse)
  }                                               //> isPal: (word: String)Boolean

  isPal("rotator")                                //> res0: Boolean = true
  isPal("cat")                                    //> res1: Boolean = false

  def isPal2(words: String): Boolean = {
    return isPal(words.toLowerCase.replaceAll("[^A-Za-z0-9]", ""))
  }                                               //> isPal2: (words: String)Boolean

  isPal2("A man, a plan, a canal, Panama!")       //> res2: Boolean = true

  def mkPal(word: String): String = {
    return word + word.reverse
  }                                               //> mkPal: (word: String)String

  mkPal("mars")                                   //> res3: String = marssram
  mkPal("3X@#")                                   //> res4: String = 3X@##@X3

  import scala.util.Random
  def mkWord(len: Int = 10): String = {
    var alphabet = "abcedfghijklmnopqrstuvwxyz"
    var rand = Random
    var i = 0
    var end = ""
    for (i <- 0 to len) {
      end += alphabet.charAt(rand.nextInt(26))
    }
    return end
  }                                               //> mkWord: (len: Int)String

  val a1 = mkWord()                               //> a1  : String = gbnwauwakrc
  val a2 = mkWord()                               //> a2  : String = qqduqmrwnfv
  val a3 = mkWord()                               //> a3  : String = drrjhctartg
  val a4 = mkWord(20)                             //> a4  : String = fdrctjosdyarffeiquccs

  def mkSentence(words: Int = 10): String = {
    var i = 0
    var rand = Random
    var end = ""
    for (i <- 0 to words-1) {
        end += mkWord(rand.nextInt(9) + 1)
      if (i == words-1) {
        end += "."
      } else {
        end += " "
      }
    }
    return end.capitalize
  }                                               //> mkSentence: (words: Int)String

  val sen1 = mkSentence()                         //> sen1  : String = Juldhishu xfsakk ltcyltqacz qmxhigovdg eoiaccfc bgruiwqkf
                                                  //| ufwttzwsv il hytmbahx ivjs.
  val sen2 = mkSentence()                         //> sen2  : String = Afvug aizu llxenjvzf xljyuomh ywfbcifd hcwm xr dhdsfeuajc
                                                  //| hbeoqj qddtve.
  val sen3 = mkSentence()                         //> sen3  : String = Surjtdrvl kqtqbdafk bspgfbrq zk dwdhdn kvhubky wxkai kvqo
                                                  //| wifze ntf.
  val sen4 = mkSentence(5)                        //> sen4  : String = Nxwi ajjzvclo soroghmho dkpb lfb.

  def shuffle(word: String): String = {
  return word.substring(word.length/2, word.length) + word.substring(0, word.length/2)
  }                                               //> shuffle: (word: String)String

  shuffle("abcdefghij")                           //> res5: String = fghijabcde
  shuffle("abcdefghijk")                          //> res6: String = fghijkabcde

  def countSubstrings(sub: String, word: String): Int = {
  return sub.r.findAllIn(word).length
  }                                               //> countSubstrings: (sub: String, word: String)Int

  countSubstrings("is", "Mississippi")            //> res7: Int = 2

  def first(a: Array[String]):String = {
  scala.util.Sorting.quickSort(a)
  return a(0)
  }                                               //> first: (a: Array[String])String

  first(Array("cat", "rat", "bat"))               //> res8: String = bat

}