LeetCode - Algorithms - 537. Complex Number Multiplication

Problem

537. Complex Number Multiplication

Java

Complex.java

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class Solution {
    public String complexNumberMultiply(String a, String b) {
        int re1 = Integer.parseInt(a.substring(0, a.indexOf("+")));
        int im1 = Integer.parseInt(a.substring(a.indexOf("+") + 1, a.length() - 1));
        Complex c1 = new Complex(re1, im1);
        int re2 = Integer.parseInt(b.substring(0, b.indexOf("+")));
        int im2 = Integer.parseInt(b.substring(b.indexOf("+") + 1, b.length() - 1));
        Complex c2 = new Complex(re2, im2);
        Complex c = c1.times(c2);
        return c.toString();        
    }
}

class Complex {
    private int re;
    private int im;

    public Complex(int real, int imag) {
        this.re = real;
        this.im = imag;
    }

    public String toString() {
        return re + "+" + im + "i";
    }

    public Complex times(Complex that) {
        int real = this.re * that.re - this.im * that.im;
        int imag = this.re * that.im + this.im * that.re;
        return new Complex(real, imag);
    }
}

Submission Detail

  • 55 / 55 test cases passed.
  • Runtime: 4 ms, faster than 81.21% of Java online submissions for Complex Number Multiplication.
  • Memory Usage: 37.6 MB, less than 17.58% of Java online submissions for Complex Number Multiplication.