整数转罗马数字

整数转罗马数字

intToRoman(num){
      let res = '';
      let map = {
        1000: 'M',
        900: 'CM',
        500: 'D',
        400: 'CD',
        100: 'C',
        90: 'XC',
        50: 'L',
        40: 'XL',
        10: 'X',
        9: 'IX',
        5: 'V',
        4: 'IV',
        1: 'I'
      };
      let keys = Object.keys(map).reverse();
      for(let i=0; i < keys.length; i++){
        while (num >= keys[i]){
          res += map[keys[i]];
          num -= keys[i];
        }
      }
      return res;
    },