寫在最前面：一道很常規的字串分割的題

leetcode【537】Complex Number Multiplication

Given two strings representing two complex numbers.

You need to return a string representing their multiplication. Note i2 = -1 according to the definition.

Example 1:

Input: "1+1i", "1+1i"
Output: "0+2i"
Explanation:
 
 (1 + i) * (1 + i) = 1 + i2 + 2 * i = 2i, and you need convert it to the form of 0+2i.

Example 2:

Input: "1+-1i", "1+-1i"
Output: "0+-2i"
Explanation: (1 - i) * (1 - i) = 1 + i2 - 2 * i = -2i, and you need convert it to the form of 0+-2i.

Note:

1. The input strings will not have extra blank.
2. The input strings will be given in the form of a+bi, where the integer a and b will both belong to the range of [-100, 100]. And the output should be also in this form.

class Solution(object):
    def complexNumberMultiply(self, a, b):
        """
        :type a: str
        :type b: str
        :rtype: str
        """
        sub1 = int(a.split('+')[0]) *int( b.split('+')[0])
        sub2 = int(a.split('+')[0]) * int(b.split('+')[1][:-1])
        sub3 = int(a.split('+')[1][:-1]) * int(b.split('+')[0])
        sub4 = int(a.split('+')[1][:-1]) * int(b.split('+')[1][:-1])
        sum = sub1 + sub4*-1
        return str(sum) + '+'+str(sub2+sub3)+'i'