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Problem

A complex number can be represented as a string on the form “real+imaginaryi” 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].
  • i^2 == -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 + i^2 + 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 + i^2 - 2 * i = -2i, and you need convert it to the form of 0+-2i.

Constraints:

  • num1 and num2 are valid complex numbers.

Code

class Solution {
    public String complexNumberMultiply(String a, String b) {
        String x[] = a.split("\\+");
        String y[] = b.split("\\+");
        
        int aReal = Integer.parseInt(x[0]);
        int aImg = Integer.parseInt(x[1].replace("i",""));
        int bReal = Integer.parseInt(y[0]);
        int bImg = Integer.parseInt(y[1].replace("i",""));
        
        return (aReal * bReal - aImg * bImg) + "+" + (aReal * bImg + aImg * bReal) + "i";
    }
}