LeetCode刷题实战537：复数乘法
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].
i2 == -1.
Given two complex numbers num1 and num2 as strings, return a string of the complex number that represents their multiplications.
实部 是一个整数，取值范围是 [-100, 100]
虚部 也是一个整数，取值范围是 [-100, 100]
i的平分 == -1
示例
示例 1：
输入：num1 = "1+1i", num2 = "1+1i"
输出："0+2i"
解释：(1 + i) * (1 + i) = 1 + i2 + 2 * i = 2i ，你需要将它转换为 0+2i 的形式。
示例 2：
输入：num1 = "1+-1i", num2 = "1+-1i"
输出："0+-2i"
解释：(1 - i) * (1 - i) = 1 + i2 - 2 * i = -2i ，你需要将它转换为 0+-2i 的形式。
解题
public class Solution {
public String complexNumberMultiply(String a, String b) {
String x[] = a.split("\\+|i");
String y[] = b.split("\\+|i");
int a_real = Integer.parseInt(x[0]);
int a_img = Integer.parseInt(x[1]);
int b_real = Integer.parseInt(y[0]);
int b_img = Integer.parseInt(y[1]);
return (a_real * b_real - a_img * b_img) + "+" + (a_real * b_img + a_img * b_real) + "i";
}
}