思路

建立数字和字符的字典映射表，遍历映射表做差，将字符添加到结果中，当差为0的时候，break退出循环。返回最后的结果output

class Solution:def intToRoman(self, num: int) -> str:if num<1:return ''num_to_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')]output=[]for key,val in num_to_map:while num>=key:num-=keyoutput.append(val)if num==0:breakreturn ''.join(output)