Counter.scala

import java.io.FileOutputStream
import scala.io.Source

object Counter {
  val INPUT = "A-large-practice.in"
  val OUTPUT = INPUT.takeWhile(_ != '.') + ".out2"
  val isConsole = false

  def main(args: Array[String]): Unit = {
    val itr = Source.fromFile(INPUT).getLines()
    val stream = if (isConsole) Console.out else new FileOutputStream(OUTPUT)
    try {
      Console.withOut(stream) {
        val sets = itr.next().toInt
        (1 to sets).foreach { set =>
          val n = itr.next()
          println(f"Case #$set: ${solve(n)}")
        }
      }
    } finally {
      stream.flush()
      if (!isConsole) stream.close()
    }
  }

  def solve(N:String):Long = {
    val n = N.toLong
    val nL = N.length
    def count(accr:String, cnt:Long):Long = accr match {
      case _ if accr == N => cnt
      case _ if accr.length + 1 < nL =>
        val newAccr = "1" + "0" * (accr.length / 2) + "9" * ((accr.length + 1) / 2)
        count(newAccr.reverse, newAccr.toLong - accr.toLong + 1 + cnt)
      case _ if accr.length < nL =>
        val newAccr = "1" + "0" * (nL -1)
        count(newAccr, newAccr.toLong - accr.toLong + cnt)
      case _  =>
        // n -1의 값을 reverse..
        val newAccr = "1" + "0" * ((nL - 1) / 2) + (n - 1).toString.take(nL / 2).reverse
        if (newAccr.reverse == newAccr || newAccr.toLong > n) n - accr.toLong + cnt
        else n - newAccr.reverse.toLong + 1 + (newAccr.toLong - accr.toLong) + cnt
    }
    count("1", 1)
  }
}