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Ejdzbikej
Asked: 2024-02-11 12:56:33 +0800 CST

查找并列出给定输入整数 DART 的所有因子

  • 772

正如主题所示，我提出了下面提出的解决方案，但我觉得它很愚蠢，可以用更有效的方式重写。

请给我一些反馈或建议。

import 'dart:io';

void main() {
  // the while true loop is here only so I don't have to hit RUN every time to check another nuber
  while (true) {
    // Prompts user for input ( on the same line )
    stdout.write("Enter the number: ");
    var userInput = int.parse(stdin.readLineSync()!);
    int divisor;
    int numberOfFactors = 0;
    var listOfFactors = [];

    for (divisor = 1; divisor <= userInput; divisor++) {
      if (userInput % divisor == 0) {
        numberOfFactors++;
        listOfFactors.add(divisor);
      }
    }

    // formats the display of end output( is that even in English? xD)
    var formattedList = listOfFactors.toString().replaceAll('[', '').replaceAll(']', '');

    if (numberOfFactors > 2) {
      print("Provided number is not prime, and the factors are ${formattedList}");
    } else {
      print(
          "Provided number is prime, because it has only two factors: ${listOfFactors[0]} and ${listOfFactors[1]}");
    }
  }
}
dart

1 个回答

  1. Best Answer

    这是您的更优化和固定的代码：

    import 'dart:io';
import 'dart:math';

void main() {
  while (true) {
    stdout.write("Enter the number: ");

    final userInput = int.parse(stdin.readLineSync()!);
    final userInputSqrt = sqrt(userInput);
    final listOfFactors = <int>[];

    for (int divisor = 1; divisor <= userInputSqrt; divisor++) {
      if (userInput % divisor == 0) {
        listOfFactors.add(divisor);
        if (divisor != userInput ~/ divisor) {
          listOfFactors.add(userInput ~/ divisor);
        }
      }
    }

    final formattedList = listOfFactors.join(', ');

    if (listOfFactors.length > 2) {
      print("Provided number is not prime, and the factors are $formattedList");
    } else {
      print("Provided number is prime, because it has only two factors: "
          "${listOfFactors[0]} and ${listOfFactors[1]}");
    }
  }
}

    还做了一些进一步的优化：

    • 删除是numberOfFactors因为我们可以检查列表的长度listOfFactors来查看找到了多少个因子。
    • formattedList使用该方法简化了创建join()。
    • 将 的类型listOfFactors从隐式更改List<dynamic>为显式List<int>。
    • （这并不是真正的优化，但我已尽可能将所有非最终变量更改为最终变量，以便更容易理解程序中哪些字段可能会发生变化）
    • 1

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