537. Complex Number Multiplication

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题目

https://leetcode.com/problems/complex-number-multiplication/description/

答案

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class Solution {
public:
    string complexNumberMultiply(string a, string b) {
        auto i = a.find('+');
        int aa = stoi(a.substr(0, i + 1));
        int ab = stoi(a.substr(i + 1, a.length() - 1));
        auto j = b.find('+');
        int ba = stoi(b.substr(0, j + 1));
        int bb = stoi(b.substr(j + 1, b.length() - 1));
        
        int ca = aa * ba - ab * bb;
        int cb = aa * bb + ab * ba;
        
        return (to_string(ca) + '+' + to_string(cb) + 'i');
    }
};

用stringstream写起来更简单

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class Solution {
public:
    string complexNumberMultiply(string a, string b) {
        std::stringstream a_in(a), b_in(b);
        int aa, ab, ba, bb;
        char tmp;
        a_in >> aa >> tmp >> ab >> tmp;
        b_in >> ba >> tmp >> bb >> tmp;
        std::stringstream ans;
        ans << aa * ba - ab * bb << '+' << aa * bb + ab * ba << 'i';
        return ans.str();
        // return to_string(aa * ba - ab * bb) + '+' + to_string(aa * bb + ab * ba) + 'i';
    }
};