以下算法是将序数转换为罗马数。它适用于大多数数字，但对于其中一些仍有问题。例如，数字500或1000不起作用，我不知道为什么。我知道我错过了一些东西;有什么帮助吗？
代码是：
function convertToRoman(num) {
//TABLE OF EQUIVALENCES
var arrConv=[{1:'I'},{2:'II'},{3:'III'},{4:'IV'},{5:'V'},{6:'VI'},{7:'VII'},{8:'VIII'},{9:'IX'},{10:'X'},{20:'XX'},{30:'XXX'},{40:'XL'},{50:'L'},{60:'LX'},{70:'LXX'},{80:'LXXX'},{90:'XC'},{100:'C'},{200:'CC'},{300:'CCC'},{400:'CD'},{500:'D'},{600:'DC'},{700:'DCC'},{800:'DCCC'},{900:'CM'},{1000:'M'},{2000:'MM'},{3000:'MMM'},{4000:'MMMM'},{5000:'MMMMM'},{6000:'MMMMMM'},{7000:'MMMMMMM'},{8000:'MMMMMMMM'},{9000:'MMMMMMMMM'}];
//First we break down the number into its units
//and create an array ex: 652 ==> [600, 50, 2]
var arr=[num.length];
arr=num.toString().split("").reverse();
var i=1;
for (var k=0;k<arr.length;k++){
arr.splice(k,1,arr[k]*i);
i*=10;
}
//We make an array of objects with the number and the roman number equivalence
var romansArray=[];
for (i=0;i<arr.length;i++){
var val=arrConv.filter(function(obj){
return obj[arr[i]];
})[0];
romansArray.push(val);
}
//I get rid of all the null values
var result=romansArray.filter(function(val){
return (val!=null);
});
//It returns the string with the roman number
return result.map(function(value,key){
return result[key][arr[key]];
}).reverse().join("");
}
答案 0 :(得分：3)
你可以改变一下
对象而不是对象数组。
访问值。
未知部分的默认值。
然后您可以省略null值的过滤。
function convertToRoman(num) {
var arrConv = { 1: 'I', 2: 'II', 3: 'III', 4: 'IV', 5: 'V', 6: 'VI', 7: 'VII', 8: 'VIII', 9: 'IX', 10: 'X', 20: 'XX', 30: 'XXX', 40: 'XL', 50: 'L', 60: 'LX', 70: 'LXX', 80: 'LXXX', 90: 'XC', 100: 'C', 200: 'CC', 300: 'CCC', 400: 'CD', 500: 'D', 600: 'DC', 700: 'DCC', 800: 'DCCC', 900: 'CM', 1000: 'M', 2000: 'MM', 3000: 'MMM', 4000: 'MMMM', 5000: 'MMMMM', 6000: 'MMMMMM', 7000: 'MMMMMMM', 8000: 'MMMMMMMM', 9000: 'MMMMMMMMM' };
var arr = num.toString().split("").reverse(),
i = 1, k;
for (k = 0; k < arr.length; k++) {
arr.splice(k, 1, arr[k] * i);
i *= 10;
}
var romansArray = [];
for (i = 0; i < arr.length; i++) {
romansArray.push(arrConv[arr[i]]||'');
}
//It returns the string with the roman number
return romansArray.reverse().join("");
}
console.log(convertToRoman(1000));
您可以使用不同的对象缩短它，以便查找和构建arr和romansArray。
function convertToRoman(num) {
var arrConv = {
0: { 1: 'I', 2: 'II', 3: 'III', 4: 'IV', 5: 'V', 6: 'VI', 7: 'VII', 8: 'VIII', 9: 'IX' },
1: { 1: 'X', 2: 'XX', 3: 'XXX', 4: 'XL', 5: 'L', 6: 'LX', 7: 'LXX', 8: 'LXXX', 9: 'XC' },
2: { 1: 'C', 2: 'CC', 3: 'CCC', 4: 'CD', 5: 'D', 6: 'DC', 7: 'DCC', 8: 'DCCC', 9: 'CM' },
3: { 1: 'M', 2: 'MM', 3: 'MMM', 4: 'MMMM', 5: 'MMMMM', 6: 'MMMMMM', 7: 'MMMMMMM', 8: 'MMMMMMMM', 9: 'MMMMMMMMM' }
},
arr = num.toString().split("").reverse(),
romansArray = arr.map(function (a, i) {
return arrConv[i][a] || '';
});
return romansArray.reverse().join("");
}
console.log(convertToRoman(1234));
答案 1 :(得分：2)
@Nina Scholz的答案是正确的（也是优雅的），但请注意你的零有问题（实际上，就像罗马人一样！）。
如果你想让你的代码工作，你必须将零添加到转换数组，第一个想法只是添加{0:''}但是，作为空字符串，过滤器函数将失败，所以你可以为键＆＃39; 0＆＃39;添加空格，最后应用修剪结果。
这样的事情：
function convertToRoman(num) {
//TABLE OF EQUIVALENCES
var arrConv=[{0:' '},{1:'I'},{2:'II'},{3:'III'},{4:'IV'},{5:'V'},{6:'VI'},{7:'VII'},{8:'VIII'},{9:'IX'},{10:'X'},{20:'XX'},{30:'XXX'},{40:'XL'},{50:'L'},{60:'LX'},{70:'LXX'},{80:'LXXX'},{90:'XC'},{100:'C'},{200:'CC'},{300:'CCC'},{400:'CD'},{500:'D'},{600:'DC'},{700:'DCC'},{800:'DCCC'},{900:'CM'},{1000:'M'},{2000:'MM'},{3000:'MMM'},{4000:'MMMM'},{5000:'MMMMM'},{6000:'MMMMMM'},{7000:'MMMMMMM'},{8000:'MMMMMMMM'},{9000:'MMMMMMMMM'}];
//First we break down the number into its units
//and create an array ex: 652 ==> [600, 50, 2]
var arr=[num.length];
arr=num.toString().split("").reverse();
var i=1;
for (var k=0;k<arr.length;k++){
arr.splice(k,1,arr[k]*i);
i*=10;
}
//We make an array of objects with the number and the roman number equivalence
var romansArray=[];
for (i=0;i<arr.length;i++){
var val=arrConv.filter(function(obj){
return obj[arr[i]];
})[0];
romansArray.push(val);
}
//I get rid of all the null values
var result=romansArray.filter(function(val){
return (val!=null);
});
//It returns the string with the roman number
return result.map(function(value,key){
return result[key][arr[key]];
}).reverse().join("").trim();
}
无论如何，正如我所说，尼娜的答案是好的。
答案 2 :(得分：0)
一种有效的数字算法，直到3999.它的工作方式类似于映射表。
function convertToRoman(num) {
var arr =[];
var arr = num.toString().split('');
var numarry =[];
var count =0;
for(var i = arr.length; i>0;i--){
numarry.push(Number(arr[count])*Math.pow(10,i-1));
++count;
}
var rom =[];
debugger;
for(var i=0;i<numarry.length;i++)
{
switch(numarry[i].toString().length){
case 1:switch(numarry[i]){
case 0 : rom.push( ''); continue;
case 1 : rom.push( 'I'); continue;
case 2 : rom.push( 'II'); continue;
case 3 : rom.push( 'III'); continue;
case 4 : rom.push( 'IV'); continue;
case 5 : rom.push( 'V'); continue;
case 6 : rom.push( 'VI'); continue;
case 7 : rom.push( 'VII'); continue;
case 8 : rom.push( 'VIII'); continue;
case 9 : rom.push( 'IX'); continue;
case 10 : rom.push( 'X'); continue;
default : rom.push( null); continue;
}continue;
case 2:switch(numarry[i]){
case 0 : rom.push( ''); continue;
case 10 : rom.push( 'X'); continue;
case 20 : rom.push( 'XX'); continue;
case 30 : rom.push( 'XXX'); continue;
case 40 : rom.push( 'XL'); continue;
case 50 : rom.push( 'L'); continue;
case 60 : rom.push( 'LX'); continue;
case 70 : rom.push( 'LXX'); continue;
case 80 : rom.push( 'LXXX'); continue;
case 90 : rom.push( 'XC'); continue;
case 100 : rom.push( 'C'); continue;
default : rom.push( null); continue;
} continue;
case 3:switch(numarry[i]){
case 0 : rom.push( ''); continue;
case 100 : rom.push( 'C'); continue;
case 200 : rom.push( 'CC'); continue;
case 300 : rom.push( 'CCC'); continue;
case 400 : rom.push( 'CD'); continue;
case 500 : rom.push( 'D'); continue;
case 600 : rom.push( 'DC'); continue;
case 700 : rom.push( 'DCC'); continue;
case 800 : rom.push( 'DCCC'); continue;
case 900 : rom.push( 'CM'); continue;
case 1000 : rom.push( 'M'); continue;
default : rom.push( null);continue;
} continue;
case 4:switch(numarry[i]){
case 0 : rom.push( '');
case 1000 : rom.push( 'M'); continue;
case 2000 : rom.push( 'MM'); continue;
case 3000 : rom.push( 'MMM'); continue;
default : rom.push( null);
} continue;
}
}
return rom.join('') ;
}
convertToRoman(500);
答案 3 :(得分：0)
这是我的答案：
function convertToRoman(num) {
var tempResult=[];
var result=[];
var romanNumbers={0:" ", 1: "I", 2: "II", 3:"III", 4:"IV", 5:"V", 6: "VI", 7:"VII", 8:"VIII", 9:"IX", 10:"X", 20:"XX", 30:"XXW", 40: "XL", 50:"L", 60:"LX", 70:"LXX", 80:"LXXX", 90:"XC", 100:"C", 400: "CD", 500: "D", 600:"DC", 700:"DCC", 800:"DCCC", 900:"CM", 1000: "M", 2000:"MM", 3000:"MMM" };
var arr= num.toString().split("");
for(var k=0; k< arr.length; k++){
arr.splice(k,1, arr[k]*1);
}
var arrLength=arr.length;
for(var k=arrLength-1; k>=0; k--){
tempResult.push(romanNumbers[arr[k] * Math.pow(10, arrLength - (k+1)) ]);
}
// Getting rid of empty spaces
for(var j=tempResult.length; j>=0; j--){
if (tempResult[j]===" "){
tempResult.splice(j, 1);
}
}
result=tempResult.reverse().join("");
return result;
}
convertToRoman(1000);
答案 4 :(得分：0)
所有这些答案都依赖于对象，因为对象没有顺序
所以使用数组不要搞砸
function romanize(num){
if(!+num){
return false;
}
var result = '';
if(num < 0){
num = Math.abs(num);
result = '-';
}
var decimal = [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 <= decimal.length; i++){
while(num % decimal[i] < num){
result += roman[i];
num -= decimal[i];
}
}
return result;
}
console.log(romanize(9999));
console.log(romanize(1989));
它也是 THE 最快
来源：selftaughtjs
编辑：至少我认为对象没有订单