algorithm - 如何缩短此 Scala 代码？

Question

我是 Scala 新手。我尝试了土耳其公民身份号码验证算法。

如何实现和优化此 Scala 代码？

您可以通过此链接找到我的 Java 版本 https://gist.github.com/hasanozgan/5601623

trait TurkishCitizenshipNumberValidator {

  private def odd(tckn: String): Int = {
    tckn.zipWithIndex.foldLeft(0) {
      (total, x) =>
        x match {
          case i if ((i._2 % 2 == 0 && i._2 < 10)) => ((i._1.asDigit) + total)
          case _ => total
        }
    }
  }

  private def even(tckn: String): Int = {
    tckn.zipWithIndex.foldLeft(0) {
      (total, x) =>
        x match {
          case i if ((i._2 % 2 == 1) && i._2 < 9) => ((i._1.asDigit) + total)
          case _ => total
        }
    }
  }

  private def total(tckn: String): Int = {
    tckn.zipWithIndex.foldLeft(0) {
      (total, x) =>
        x match {
          case i if (i._2 < 10) => ((i._1.asDigit) + total)
          case _ => total
        }
    }
  }

  def turkishCitizenshipNumberValidator(t: String): Boolean = {
    val digit10 = total(t) % 10
    val digit9 = ((odd(t) * 7) - even(t)) % 10

    ((t(9).asDigit == digit9) && t(10).asDigit == digit10)
  }
}

object test extends TurkishCitizenshipNumberValidator {
  // http://tckimliknouretici.appspot.com/
    turkishCitizenshipNumberValidator("29419391592")
                                                  //> res0: Boolean = true
}

Answer 1

如果你想要它既紧凑又清晰，并且需要基本的输入验证(正确的长度，东西是数字)，我会

def turkishCitizenshipNumberValidator(t: String): Boolean = {
  if (t.length != 11 || !t.forall(_.isDigit)) false
  else {
    val n = t.map(_.asDigit)
    val evens = n.grouped(2).take(5).map(_(0)).sum
    val odds = n.grouped(2).take(4).map(_(1)).sum
    n(10) == (n.take(10).sum % 10) && n(9) == ((odds*7 - evens) % 10)
  }
}

此处的键使用分组将字符串分成偶数对和奇数对，并将数字映射到开头的数字，因此使用它们不会太麻烦。

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编辑:如果您想混淆您的代码，试试这个!

def tCNV(t: String) = t.map(_.asDigit).foldLeft(Seq(0,0,0)){ (v,n) => v(2) match {
  case 10 => Seq(v(0)-n,v(1),0); case 9 => Seq(v(0)+n,v(1)-n,10)
  case i => Seq(v(0)+n, v(1)+n*(7*(i%2)+(i%2-1)), i+1)
}}.take(2).map(_%10).forall(_ == 0)