537. Complex Number Multiplication

Problem:

Given two strings representing two complex numbers.

You need to return a string representing their multiplication. Note i2 = -1 according to the definition.

Example 1:

Input: "1+1i", "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: "1+-1i", "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.

Note:

1. The input strings will not have extra blank.
2. The input strings will be given in the form of a+bi, where the integer a and b will both belong to the range of [-100, 100]. And the output should be also in this form.

思路：

Solution (C++):

string complexNumberMultiply(string a, string b) {
    int ra, ia, rb, ib;
    char buff;
    string res;
    stringstream aa(a), bb(b);
    
    aa >> ra >> buff >> ia >> buff;
    bb >> rb >> buff >> ib >> buff;
    res = to_string(ra*rb - ia*ib) + "+" + to_string(ra*ib+ia*rb) + "i";
    return res;
}

性能：

Runtime: 0 ms  Memory Usage: 5.9 MB

思路：

Solution (C++):

性能：

Runtime: ms  Memory Usage: MB