537. Complex Number Multiplication

题目大意：

　　　　给出a， b两个用字符串表示的虚数，求a*b

题目思路：

　　　　偷了个懒，Python3的正则表达式匹配了一下，当然acm里肯定是不行的

 class Solution:
     def complexNumberMultiply(self, a, b):
         """
         :type a: str
         :type b: str
         :rtype: str
         """
         match = re.search(r'([+-]*\d+)[+-]([+-]*\d+)i$', a)
         x1 = int(match.group(1))
         y1 = int(match.group(2))
         match = re.search(r'([+-]*\d+)[+-]([+-]*\d+)i$', b)
         x2 = int(match.group(1))
         y2 = int(match.group(2))
         ans = ''
         ans = ans + str(x1*x2 - y1*y2) + '+'
         ans = ans + str(x1*y2 + x2*y1) + 'i'
         return ans