12 Integer to Roman

野性酷女 2022-08-09 02:15 33阅读 0赞

罗马数字的规则

<table> 
 <thead> 
  <tr> 
   <th>基本字符</th> 
   <th>I</th> 
   <th>V</th> 
   <th>X</th> 
   <th>L</th> 
   <th>C</th> 
   <th>D</th> 
   <th>M</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>对应的数字</td> 
   <td>1</td> 
   <td>5</td> 
   <td>10</td> 
   <td>50</td> 
   <td>100</td> 
   <td>500</td> 
   <td>1000</td> 
  </tr> 
 </tbody> 
</table>

1.  相同的数字连写、所表示的数等于这些数字相加得到的数、如：Ⅲ=3；
2.  小的数字在大的数字的右边、所表示的数等于这些数字相加得到的数、 如：Ⅷ=8、Ⅻ=12；
3.  小的数字、（限于 Ⅰ、X 和 C）在大的数字的左边、所表示的数等于大数减小数得到的数、如：Ⅳ=4、Ⅸ=9；
4.  正常使用时、连写的数字重复不得超过三次。（表盘上的四点钟“IIII”例外）；
5.  在一个数的上面画一条横线、表示这个数扩大 1000 倍。  
    自己写的第一个版本

public class No12 {
    
        public static void main(String[] args) {
            System.out.println(intToRoman(9));
        }
    
        public static String intToRoman(int num) {
    
            String Roman = "";
    
            int M = num / 1000;
            num = num % 1000;
            for (int i = 0; i < M; i++) {
                Roman = Roman + "M";
            }
    
            int D = num / 500;
            num = num % 500;
            if (D == 0) {
                int C = num / 100;
                num = num % 100;
                if (C == 4)
                    Roman = Roman + "CD";
                else
                    for (int i = 0; i < C; i++) {
                        Roman = Roman + "C";
                    }
            } else {
                int C = num / 100;
                num = num % 100;
                if (C == 4)
                    Roman = Roman + "CM";
                else {
                    Roman = Roman + "D";
                    for (int i = 0; i < C; i++) {
                        Roman = Roman + "C";
                    }
                }
            }
    
            int L = num / 50;
            num = num % 50;
            if (L == 0) {
                int X = num / 10;
                num = num % 10;
                if (X == 4)
                    Roman = Roman + "XL";
                else
                    for (int i = 0; i < X; i++) {
                        Roman = Roman + "X";
                    }
            } else {
                int X = num / 10;
                num = num % 10;
                if (X == 4)
                    Roman = Roman + "XC";
                else {
                    Roman = Roman + "L";
                    for (int i = 0; i < X; i++) {
                        Roman = Roman + "X";
                    }
                }
            }
    
            int V = num / 5;
            num = num % 5;
            if (V == 0) {
                int I = num;
                if (I == 4)
                    Roman = Roman + "IV";
                else
                    for (int i = 0; i < I; i++) {
                        Roman = Roman + "I";
                    }
            } else {
                int I = num;
                if (I == 4)
                    Roman = Roman + "IX";
                else {
                    Roman = Roman + "V";
                    for (int i = 0; i < I; i++) {
                        Roman = Roman + "I";
                    }
                }
            }
            return Roman;
        }
    }

网上看到的第二个版本

public class No12_2 {
    
        public static void main(String[] args) {
            System.out.println(intToRoman(1234));
        }
    
        public static String intToRoman(int num) {
    
            int[] nums = { 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 };
    
            String[] str = { "M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX",
                    "V", "IV", "I" };
    
            String Roman = "";
    
            for (int i = 0; i < nums.length; i++) {
                while (num >= nums[i]) {
                    num = num - nums[i];
                    Roman = Roman + str[i];
                }
            }
    
            return Roman;
        }
    
    }