【字符串】537. 复数乘法

题目：

 

 

 

解答：

 

 

class Solution {
public:
    string complexNumberMultiply(string a, string b) 
    {
        int a1 = stoi(a);
        int b1 = stoi(b);

        int i = 0;
        int j = 0;

        while (a[i] != '+') 
        {
            i++;
        }
        while (b[j] != '+')
        {
            j++;
        }

        a = a.substr(i + 1);
        b = b.substr(j + 1);
        int a2 = stoi(a);
        int b2 = stoi(b);

        string res1 = to_string(a1 * b1 - a2 * b2);
        string res2 = to_string(a1 * b2 + a2 * b1);
        
        return res1 + "+" + res2 + "i";
    }
};