Complex Number Multiplication

A complex number can be represented as a string on the form "**real**+**imaginary**i" where:

• real is the real part and is an integer in the range [-100, 100].
• imaginary is the imaginary part and is an integer in the range [-100, 100].
• i2 == -1.

Given two complex numbers num1 and num2 as strings, return a string of the complex number that represents their multiplications.

Example 1:

Input: num1 = "1+1i", num2 = "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: num1 = "1+-1i", num2 = "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.

Constraints:

• num1 and num2 are valid complex numbers.

SOLUTION:

class Solution:
    def complexNumberMultiply(self, num1: str, num2: str) -> str:
        a, b = num1.split("+")
        c, d = num2.split("+")
        a = int(a)
        b = int(b[:-1])
        c = int(c)
        d = int(d[:-1])
        return "{}+{}i".format(a*c-b*d, a*d+b*c)