qiaoxu123
11/13/2018 - 11:55 PM

537. Complex Number Multiplication

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:

The input strings will not have extra blank. 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.

test.cpp
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struct ComplexInt {
    int real;
    int imag;
    
    ComplexInt(string c) {
        int ppos = 0;
        while(c[ppos] != '+') ppos += 1;
        real = stoi(c.substr(0, ppos));
        imag = stoi(c.substr(ppos + 1, c.size() - ppos - 2)); // start after '+' and end before 'i'
    }
    
    ComplexInt(int r, int i) : real(r), imag(i) {}
    
    string ToString() {
        return to_string(real) + "+" + to_string(imag) + "i";
    }
    
    ComplexInt operator *(const ComplexInt& rhs) const {
        return ComplexInt((real * rhs.real) - (imag * rhs.imag), (real * rhs.imag) + (imag * rhs.real));
    }
};

class Solution {
public:
    string complexNumberMultiply(string a, string b) {
        return (ComplexInt(a) * ComplexInt(b)).ToString();
    }
};