【leetcode】Integer to Roman

Question ： 

Given an integer, convert it to a roman numeral.

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

Anwser 1 ：    

class Solution {public:    string intToRoman(int num) {        // Start typing your C/C++ solution below        // DO NOT write int main() function            string res;                string symbol[]={"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};        int value[]={1000,900,500,400,100,90,50,40,10,9,5,4,1};            int i = 0;    while(num != 0){    if(num >= value[i]){    // minus largest number    num -= value[i];    res += symbol[i];    } else {            i++;       }    }    return res;    }};

Anwser 2 ：   

class Solution {public:    string intToRoman(int num) {        // Start typing your C/C++ solution below        // DO NOT write int main() function            char symbol[7] = {'I', 'V', 'X', 'L', 'C', 'D', 'M'};        string res = "";                int scale = 1000;        for (int i = 6; i >= 0; i -= 2)        {            int digit = num / scale;            num2roman(digit, res, symbol + i);            num %= scale;            scale /= 10;        }                return res;    }        void num2roman(int num, string& res, char symbols[])    {        if (num == 0)            return;        if (num <= 3)            res.append(num, symbols[0]);        else if (num == 4)        {            res.append(1, symbols[0]);            res.append(1, symbols[1]);        }        else if (num <= 8)        {            res.append(1, symbols[1]);            res.append(num - 5, symbols[0]);        }        else        {            res.append(1, symbols[0]);            res.append(1, symbols[2]);        }    }};