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在JavaScript中将数字转换为罗马数字

javascriptroman-numerals
96

我该如何将整数转换为罗马数字？

function romanNumeralGenerator (int) {

}
例如，看下面的样例输入和输出：
1 = "I"
5 = "V"
10 = "X"
20 = "XX"
3999 = "MMMCMXCIX"

注意：仅支持1到3999之间的数字。

96个回答
2

我刚刚在freecodecamp上制作了这个。它可以很容易地扩展。

function convertToRoman(num) {

  var roman ="";

  var values = [1000,900,500,400,100,90,50,40,10,9,5,4,1];
  var literals = ["M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"];


  for(i=0;i<values.length;i++){
    if(num>=values[i]){
      if(5<=num && num<=8) num -= 5;
      else if(1<=num && num<=3) num -= 1;
      else num -= values[i];
      roman += literals[i];
      i--;
    }
  }


 return roman;
}
2

这个函数适用于每个数字中的不同字符集。要添加另一个数字，请在罗马数字字符串的1位、5位和下一个1位上添加。这很好，因为你只需要知道下一个使用的字符集就可以更新它。

function toRoman(n){
  var d=0,o="",v,k="IVXLCDM".split("");
                    
  while(n!=0){
    v=n%10,x=k[d],y=k[d+1],z=k[d+2];
    o=["",x,x+x,x+x+x,x+y,y,y+x,y+x+x,y+x+x+x,x+z][v]+o;
    n=(n-v)/10,d+=2;
  }
  
  return o
}

var out = "";

for (var i = 0; i < 100; i++) {
  out += toRoman(i) + "\n";
}

document.getElementById("output").innerHTML = out;
<pre id="output"></pre>

2

如果这个数字在 HTMLElement 中（例如 span），我们建议添加 HTML 属性 data-format：

Number.prototype.toRoman = function() {
  var e = Math.floor(this),
    t, n = "",
    i = 3999,
    s = 0;
  v = [1e3, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1], r = ["M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"];
  if (e < 1 || e > i) return "";
  while (s < 13) {
    t = v[s];
    while (e >= t) {
      e -= t;
      n += r[s]
    }
    if (e == 0) return n;
    ++s
  }
  return ""
};
var fnrom = function(e) {
  if (parseInt(e.innerHTML)) {
    e.innerHTML = parseInt(e.innerHTML).toRoman()
  }
};
setTimeout(function() {
  [].forEach.call(document.querySelectorAll("[data-format=roman]"), fnrom)
}, 10)
Phase <span data-format="roman">4</span> Sales

2

function convertToRoman(num) {

  var romans = {
    1000: 'M',
    900: 'CM',
    500: 'D',
    400: 'CD',
    100: 'C',
    90: 'XC',
    50: 'L',
    40: 'XL',
    10: 'X',
    9: 'IX',
    5: 'V',
    4: 'IV',
    1: 'I'
  };
  var popped, rem, roman = '',
    keys = Object.keys(romans);
  while (num > 0) {
    popped = keys.pop();
    m = Math.floor(num / popped);
    num = num % popped;
    console.log('popped:', popped, ' m:', m, ' num:', num, ' roman:', roman);
    while (m-- > 0) {
      roman += romans[popped];
    }
    while (num / popped === 0) {
      popped = keys.pop();
      delete romans[popped];
    }
  }
  return roman;
}
var result = convertToRoman(3999);
console.log(result);
document.getElementById('roman').innerHTML = 'Roman: ' + result;
p {
  color: darkblue;
}
<p>Decimal: 3999</p>
<p id="roman">Roman:</p>

2

function convertToRoman(num) {
  let roman = ["M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"];
  let arabic = [1000, 900, 500, 400, 100,  90,   50,  40,   10,   9,   5,   4,    1];
  let index = 0;
  let result = "";
  while (num > 0) {
    if (num >= arabic[index]) {
      result += roman[index];
      num -= arabic[index];
    } else index++;
  }

  return result;
}

1
这适用于所有只需要罗马数字M及以下的数字。
function convert(num) {
  var code = [
    [1000, "M"], [900, "CM"], [800, "DCCC"], [700, "DCC"], [600, "DC"],
    [500, "D"], [400, "CD"], [300, "CCC"], [200, "CC"], 
    [100, "C"], [90, "XC"], [80, "LXXX"], [70, "LXX"], [60, "LX"], 
    [50, "L"], [40, "XL"], [30, "XXX"], [20, "XX"], 
    [10, "X"], [9, "IX"], [8, "VIII"], [7, "VII"], [6, "VI"], 
    [5, "V"], [4, "IV"], [3, "III"], [2, "II"], [1, "I"],
  ];

  var rom = "";
  for(var i=0; i<code.length; i++) {
    while(num >= code[i][0]) {
      rom += code[i][1];
      num -= code[i][0];
    }
  }
  return rom;
}
1

有几种方法可以实现这个目标。我个人更喜欢使用对象并遍历键值对：

const solution=(n)=>{
   const romanLetters ={M:1000, CM:900, D:500, CD:400, C:100, XC:90, L:50, XL:40, X:10, IX:9, V:5, IV:4, I:1};
   let romanNumber ='';
   let valuesArr = Object.values(romanLetters);

   for(let i in valuesArr){
        while (n - valuesArr[i] >= 0){
            romanNumber+=Object.keys(romanLetters)[i]; 
            n-=valuesArr[i];
        }
   }
   return romanNumber;
}
1
我认为我的解决方案更易读、易懂。
var intToRoman = function(num) {
    let symbolMap = ['I','V','X','L','C','D','M','P','Q'];

    if (num < 1 || num > 9999) {
        return null;
    }

    let i = 0;
    let result = '';

    while (num) {
        let digit = num % 10;
        num = parseInt(num / 10);

        switch (digit) {
            case 1: result = symbolMap[i] + result;
                break;
            case 2: result = symbolMap[i] + symbolMap[i] + result;
                break;
            case 3: result = symbolMap[i] + symbolMap[i] + symbolMap[i] + result;
                break;
            case 4: result = symbolMap[i] + symbolMap[i+1] + result;
                break;
            case 5: result = symbolMap[i+1] + result;
                break;
            case 6: result = symbolMap[i+1] + symbolMap[i] + result;
                break;
            case 7: result = symbolMap[i+1] + symbolMap[i] + symbolMap[i] + result;
                break;
            case 8: result = symbolMap[i+1] + symbolMap[i] + symbolMap[i] + symbolMap[i] + result;
                break;
            case 9: result = symbolMap[i] + symbolMap[i+2] + result;
                break;
        }
        i += 2;
    }

    return result;
 };
1
function toRoman(n) {
    var decimals = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1];
    var roman = ['M', 'CM', 'D', 'CD', 'C', 'XC', 'L', 'XL', 'X', 'IX', 'V', 'IV', 'I'];

    for (var i = 0; i < decimals.length; i++) {
        if(n < 1)
            return "";       

        if(n >= decimals[i]) {
            return roman[i] + toRoman(n - decimals[i]);        
        }
    }
}
1
function convertToRoman (num) {
    var v = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1];
    var r = ['M', 'CM', 'D', 'CD', 'C', 'XC', 'L', 'XL', 'X', 'IX', 'V', 'IV', 'I'];
    var s = "";
    for(i = 0; i < v.length; i++) {
        value = parseInt(num/v[i]);
        for(j = 0; j < value; j++) {
            s += r[i];
        }
        num = num%v[i];
    }
    return s;
}
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