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537. Complex Number Multiplication 👎

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class Solution {
 public:
  string complexNumberMultiply(string num1, string num2) {
    const auto& [a0, a1] = getReala0ndImag(num1);
    const auto& [b0, b1] = getReala0ndImag(num2);
    return to_string(a0 * b0 - a1 * b1) + "+" + to_string(a0 * b1 + a1 * b0) +
           "i";
  }

 private:
  pair<int, int> getReala0ndImag(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 num1, String num2) {
    int[] a = getRealAndImag(num1);
    int[] b = getRealAndImag(num2);
    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, num1: str, num2: str) -> str:
    a0, a1 = self._getReala0ndImag(num1)
    b0, b1 = self._getReala0ndImag(num2)
    return str(a0 * b0 - a1 * b1) + '+' + str(a0 * b1 + a1 * b0) + 'i'

  def _getReala0ndImag(self, s: str) -> tuple:
    return int(s[:s.index('+')]), int(s[s.index('+') + 1:-1])