pig

gistfile1.scala

object Succ {
  def main(args: Array[String]) {
    assert(succ("") == "")
    assert(succ("3") == "4")
    assert(succ("R2D3") == "R2D4")
    assert(succ("R293") == "R294")
    assert(succ("R2D9") == "R2E0")
    assert(succ("A99") == "B00")
    assert(succ("Z99") == "AA00")
    assert(succ("Zz99") == "AAa00")
    assert(succ("9Z") == "10A")
    println("finished")
  }
  
  def succ1(ch: Char): String = ch match {
    case '9' => ("10")
    case 'z' => ("aa")
    case 'Z' => ("AA")
    case x:Char => "0" ++ (x + 1).toChar.toString
  }
  
  def add(ch:Char, prevRs:String): String = prevRs.head match {
    case '0' => '0'.toString ++ ch.toString + prevRs.tail
    case _ => succ1(ch) ++ prevRs.tail
  }

  def succ(s: String): String = {
    s match {
      case "" => ""
      case _ =>  {
        val tempRs = s.foldRight("1") {(ch,rs) => add(ch,rs)}
        if(tempRs.head == '0') tempRs.tail else tempRs
      }
    }
  }
}