12. Integer to Roman

Thinking:

Method1: Compare and append. Symbol Value I 1 IV 4 V 5 IX 9 X 10 XL 40 L 50 XC 90 C 100 CD 400 D 500 CM 900 M 1000

  class Solution {
      public String intToRoman(int num) {
          if(num <= 0) return "";
          String[] roman = {"M", "CM","D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"};
          int[] n = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};
          StringBuilder sb = new StringBuilder();
          for(int i = 0; num != 0; i++){
              while(num >= n[i]){
                  num -= n[i];
                  sb.append(roman[i]);
              }
          }
          return sb.toString();
      }
  }