12.cpp

class Solution {
public:
  string intToRoman(int num) {
    string res;
    while (num >= 1000) {
      res += 'M';
      num -= 1000;
    }
    while (num >= 900) {
      res += "CM";
      num -= 900;
    }
    while (num >= 500) {
      res += 'D';
      num -= 500;
    }
    while (num >= 400) {
      res += "CD";
      num -= 400;
    }
    while (num >= 100) {
      res += 'C';
      num -= 100;
    }
    while (num >= 90) {
      res += "XC";
      num -= 90;
    }
    while (num >= 50) {
      res += 'L';
      num -= 50;
    }
    while (num >= 40) {
      res += "XL";
      num -= 40;
    }
    while (num >= 10) {
      res += 'X';
      num -= 10;
    }
    while (num >= 9) {
      res += "IX";
      num -= 9;
    }
    while (num >= 5) {
      res += 'V';
      num -= 5;
    }
    while (num >= 4) {
      res += "IV";
      num -= 4;
    }
    while (num >= 1) {
      res += 'I';
      num -= 1;
    }
    return res;
  }
};