12. Integer to Roman

Given an integer, convert it to a roman numeral.

Input is guaranteed to be within the range from 1 to 3999.

String类题目

| I | V | X | L | C | D | M | | --- | --- | --- | --- | --- | --- | --- | --- | | 1 | 5 | 10 | 50 | 100 | 500 | 1000 |

这个题目的注意点是罗马数字4，9，40，90 ... 的写法有所不同，需要单独处理。

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