Given an integer, convert it to a roman numeral.

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

思路

这一题需要我们把一个1-3999的整数，转换成罗马数字。

注意罗马数字的组成规则即可。1000是M，900是CM，500是D，400是CD。跨位不受影响。

举例：

1999是 MCMXCIX –> M/CM/XC/IX/

1876是 MDCCCLXXVI –> M/DCCC/LXX/VI/

罗马数字简直反人类，活该外国小朋友学不好数学哈哈哈哈哈

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class Solution(object):
    def intToRoman(self, num):
        """
        :type num: int
        :rtype: str
        """
        basics = ["I","II","III","IV","V","VI","VII","VIII","IX"]
        res = ""
        m = num / 1000
        if (m > 0):
            num = num - 1000 * m
            for i in range(m):
                res += "M"
            
        if (num >= 900):
            res += "CM"
            num = num - 900
        elif (num < 900 and num >= 500):
            res += "D"
            num = num - 500
        elif (num >= 400 and num < 500):
            res += "CD"
            num = num - 400
        
        c = num / 100
        
        if ( c > 0 ):
            num = num - 100 * c
            for i in range(c):
                res += "C"
                
        if (num >= 90):
            res += "XC"
            num = num - 90
        elif (num < 90 and num >= 50):
            res += "L"
            num = num - 50
        elif (num >= 40 and num < 50):
            res += "XL"
            num = num - 40
        
        x = num / 10
        
        if ( x > 0 ):
            num = num - 10 * x
            for i in range(x):
                res += "X"
        
        if (num > 0):
            res += basics[num-1]
        
        return res