integer-to-roman.java

class Solution {
    public String intToRoman(int num) {
        StringBuilder res = new StringBuilder();
        int quotient;

        //case num > 1000:
        quotient = num / 1000;
        num = num - 1000 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("M");
        //case 900:
        quotient = num / 900;
        num = num - 900 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("CM");
        //case 500:
        quotient = num / 500;
        num -= 500 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("D");
        //case 400:
        quotient = num / 400;
        num -= 400 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("CD");
        //case 100:
        quotient = num / 100;
        num -= 100 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("C");
        //case 90:
        quotient = num / 90;
        num -= 90 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("XC");
        //case 50:
        quotient = num / 50;
        num -= 50 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("L");
        //case 40:
        quotient = num / 40;
        num -= 40 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("XL");
        //case 10:
        quotient = num / 10;
        num -= 10 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("X");
        //case 9:
        quotient = num / 9;
        num -= 9 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("IX");
        //case 5:
        quotient = num / 5;
        num -= 5 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("V");
        //case 4:
        quotient = num / 4;
        num -= 4 * quotient;
        for (int i = 0; i < quotient; i++)
            res.append("IV");
        //case 1:
        for (int i = 0; i < num; i++)
            res.append("I");

        return res.toString();
    }
}