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537. Complex Number Multiplication 👎

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class Solution {
 public:
  string complexNumberMultiply(string a, string b) {
    const auto& [A, B] = getRealAndImag(a);
    const auto& [C, D] = getRealAndImag(b);
    return to_string(A * C - B * D) + "+" + to_string(A * D + B * C) + "i";
  }

 private:
  pair<int, int> getRealAndImag(const string& s) {
    const string& real = s.substr(0, s.find_first_of('+'));
    const string& imag = s.substr(s.find_first_of('+') + 1);
    return {stoi(real), stoi(imag)};
  };
};

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class Solution {
  public String complexNumberMultiply(String a, String b) {
    int[] A = getRealAndImag(a);
    int[] B = getRealAndImag(b);
    return String.valueOf(A[0] * B[0] - A[1] * B[1]) + "+" +
        String.valueOf(A[0] * B[1] + A[1] * B[0]) + "i";
  }

  private int[] getRealAndImag(final String s) {
    final String real = s.substring(0, s.indexOf('+'));
    final String imag = s.substring(s.indexOf('+') + 1, s.length() - 1);
    return new int[] {Integer.valueOf(real), Integer.valueOf(imag)};
  }
}

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class Solution:
  def complexNumberMultiply(self, a: str, b: str) -> str:
    def getRealAndImag(s: str) -> tuple:
      return int(s[:s.index('+')]), int(s[s.index('+') + 1:-1])

    A, B = getRealAndImag(a)
    C, D = getRealAndImag(b)

    return str(A * C - B * D) + '+' + str(A * D + B * C) + 'i'