leetcode 13. 罗马数字转整数

代码：

class Solution(object):
    def romanToInt(self, s):
        """
        :type s: str
        :rtype: int
        """
        dict1 = {'I':1,'V':5,'X':10,'L':50,'C':100,'D':500,'M':1000}
        nums = 0
        t = len(s)
        i= 0
        while i<t :
            if s[i]=='I':
                if i+1 == t:
                    nums+=dict1.get(s[i])
                    i+=1
                else:
                    if s[i+1] =='V':
                        nums+=4
                        i+=2
                    elif s[i+1]=='X':
                        nums+=9
                        i+=2
                    else:
                        nums+=dict1.get(s[i])
                        i+=1
            elif s[i]=='X':
                if i+1 == t:
                    nums+=dict1.get(s[i])
                    i+=1
                else:
                    if s[i+1] =='L':
                        nums+=40
                        i+=2
                    elif s[i+1]=='C':
                        nums+=90
                        i+=2
                    else:
                        nums+=dict1.get(s[i])
                        i+=1
                    
            elif s[i]=='C':
                if i+1 == t:
                    nums+=dict1.get(s[i])
                    i+=1
                else:
                    if s[i+1] =='D':
                        nums+=400
                        i+=2
                    elif s[i+1]=='M':
                        nums+=900
                        i+=2
                    else:
                        nums+=dict1.get(s[i])
                        i+=1
            else:
                nums+=dict1.get(s[i])
                i+=1
        return nums