我正在嘗試在Dart中將整數轉換為羅馬

我是飛鏢的新手。我試圖將整數轉換為羅馬。但它什么也不回傳。你們能幫幫我嗎？這是我的代碼示例。此代碼來自 Leetcode 問題部分。

class Solution {
  String intToRoman(int num) {
       List<int> numbers = [1,4,5,9,10,40,50,90,100,400,500,900,1000];
       List<String> romans = ["I","IV","V","IX","X","XL","L","XC","C","CD","D","CM", "M"];
       int index = romans.length - 1;
       String roman = '';
      
      for(num >0;numbers[index]<=num;){
          roman  = romans[index];
          num -= numbers[index];
          index -= 1;
      }
      
      return roman;
  }
    
}

uj5u.com熱心網友回復：

只需在邏輯上稍作更改。在 dartpad 上嘗試：https ://dartpad.dev/?id

void main() {

print (intToRoman(30)); // result: XXX

}

 String intToRoman(int num) {
   List<int> numbers = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1];
   List<String> romans = ["M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"];
      
   String roman = '';
      
   for (int i = 0; i < numbers.length; i  ) {
     while (num >= numbers[i]) {
      roman  = romans[i];
      num -= numbers[i];
    }
   }
      
   return roman;
}

uj5u.com熱心網友回復：

此解決方案基于Wiki：

class Solution {
  /// digit: 3=Thousands(103), 2=Hundreds(102), 1=Tens(10), 0=Units(1)
  /// Range for roman numerals: 1...3999
  static final romanNumerals = <int,Map<int,String>>{
    1 : {3:'M', 2:'C', 1:'X', 0:'I'},
    2 : {3:'MM', 2:'CC', 1:'XX', 0:'II'},
    3 : {3:'MMM', 2:'CCC', 1:'XXX', 0:'III'},
    4 : {2:'CD', 1:'XL', 0:'IV'},
    5 : {2:'D', 1:'L', 0:'V'},
    6 : {2:'DC', 1:'LX', 0:'VI'},
    7 : {2:'DCC', 1:'LXX', 0:'VII'},
    8 : {2:'DCCC', 1:'LXXX', 0:'VIII'},
    9 : {2:'CM', 1:'XC', 0:'IX'},
  };
  /* ---------------------------------------------------------------------------- */
  Solution();
  /* ---------------------------------------------------------------------------- */
  String intToRoman(int number) {
    if (number < 1 || number >= 4000) return '';
    
    var list = number.toString().split('').map(int.parse).toList();
    var buffer = StringBuffer();
    final len = list.length;
    
    for (var i = 0; i < len; i  ) {
      var digit = list[i];
      if (digit == 0) continue;
      buffer.write(romanNumerals[digit]![len - 1 - i]);
    }

    return buffer.toString();
  }
  /* ---------------------------------------------------------------------------- */
  void intToRoman2(int number) {
    print(intToRoman(number));
  }
}

void main(List<String> args) {
  Solution()
  ..intToRoman2(3)
  ..intToRoman2(58)
  ..intToRoman2(1994)
  ;
}

輸出：

III
LVIII
MCMXCIV

這段代碼已經發送到 LeetCode，結果如下：

Runtime: 1130 ms, faster than 27.96% of Dart online submissions for Integer to Roman.
Memory Usage: 150.5 MB, less than 44.09% of Dart online submissions for Integer to Roman.

uj5u.com熱心網友回復：

為什么不使用簡單的方法？

我使用此擴展程式將英文數字轉換為波斯數字

extension StringExtensions on String {
  String persianNumber() {
    String number = this;
    number = number.replaceAll("1", "?");
    number = number.replaceAll("2", "?");
    number = number.replaceAll("3", "?");
    number = number.replaceAll("4", "?");
    number = number.replaceAll("5", "?");
    number = number.replaceAll("6", "?");
    number = number.replaceAll("7", "?");
    number = number.replaceAll("8", "?");
    number = number.replaceAll("9", "?");
    number = number.replaceAll("0", "?");
    return number;
  }
}

extension IntExtensions on int {
  String persianNumber() {
    String number = this.toString();
    number = number.replaceAll("1", "?");
    number = number.replaceAll("2", "?");
    number = number.replaceAll("3", "?");
    number = number.replaceAll("4", "?");
    number = number.replaceAll("5", "?");
    number = number.replaceAll("6", "?");
    number = number.replaceAll("7", "?");
    number = number.replaceAll("8", "?");
    number = number.replaceAll("9", "?");
    number = number.replaceAll("0", "?");
    return number;
  }
}

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