![image-20230316104717043](https://img.slcp.top/image-20230316104717043.png)

## 代码
~~~java
class Solution {
    public String complexNumberMultiply(String num1, String num2) {
        int[] arr1 = explainNumStr(num1);
        int[] arr2 = explainNumStr(num2);

//i平方等于-1 这里直接操作
        int ans1 = (arr1[0] * arr2[0]) - (arr1[1] * arr2[1]);
        int ans2 = arr1[0] * arr2[1] + arr2[0] * arr1[1];

StringBuilder sb = new StringBuilder();
        sb.append(ans1).append('+').append(ans2).append('i');
        return sb.toString();
    }

int[] explainNumStr(String str){
        //1+-1i
        int num1 = 0;
        int num2 = 0;
        int flag1 = 1;
        int flag2 = 1;
        int idx = -1;

if (str.charAt(idx+1) == '-'){
            flag1 = -1;
            idx++;
        }
        while (str.charAt(++idx) != '+'){
            num1 = num1 * 10 + (str.charAt(idx)-'0');
        }
        if (str.charAt(idx+1) == '-'){
            flag2 = -1;
            idx++;
        }
        while (str.charAt(++idx) != 'i'){
            num2 = num2 * 10 + (str.charAt(idx)-'0');
        }

return new int[]{num1 * flag1, num2 * flag2};
    }
}
~~~

537. 复数乘法

目录