0394-decode-string.scala

objectSolution {

defdecodeString(s: String):String= {
val (str, res) = decodeStringRecursive(s, 0)
 str
 }

defdecodeStringRecursive(input: String, start: Int): (String, Int) = {
valresult=newStringBuilder()
vari= start
while(i < input.length){
 input(i) match {
case x if x>='0'&& x<='9'=>
valcurrNum= input.substring(i, input.indexOf('[', i)).toInt
val (str, maxI) = decodeStringRecursive(input, input.indexOf('[', i)+1)
 i = maxI
 result.append(str * currNum)
case x if x >='a'&& x <='z'=>
 (result.append(x), i)
case']'=>
return (result.toString, i)
case _ =>
 }
 i+=1
 }
 (result.toString, i)
 }

}