Last updated on October 5th, 2024 at 06:03 pm

Here, We see Complex Number Multiplication LeetCode Solution. This Leetcode problem is done in many programming languages like C++, Java, JavaScript, Python, etc. with different approaches.

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Complex Number Multiplication LeetCode Solution

Problem Statement

A complex number can be represented as a string on the form "real+imaginaryi" where:

• real is the real part and is an integer in the range [-100, 100].
• imaginary is the imaginary part and is an integer in the range [-100, 100].
• i2 == -1.

Given two complex numbers num1 and num2 as strings, return a string of the complex number that represents their multiplications.

Example 1:
Input: num1 = “1+1i”, num2 = “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: num1 = “1+-1i”, num2 = “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.

1. Complex Number Multiplication LeetCode Solution C++

class Solution {
public:
    string complexNumberMultiply(string num1, string num2) {
        string res = "" ;
        int a1 = real(num1) ;
        int a2 = real(num2) ;
        int b1 = complex(num1) ;
        int b2 = complex(num2) ;
        res = res + to_string(a1*a2-b1*b2)+'+'+to_string(a1*b2+a2*b1)+'i' ;
        return res ;        
    }

    int real(string str){
        int i = 0 ;
        string real = "" ;
        while(str[i]!='+'){
            real += str[i] ;
            i++ ;
        }
        return stoi(real) ;
    }
    
    int complex(string str){
        int i = 0 ;
        string complex = "" ;
        while(str[i]!='+'){
            i++ ;
        }
        i++ ;
        while(str[i]!='i'){
            complex += str[i] ;
            i++ ;
        }
        return stoi(complex) ;
    }
};

2. Complex Number Multiplication Solution Java

class Solution {
    public String complexNumberMultiply(String num1, String num2) {
        String[] a = num1.split("\\+|i");
        String[] b = num2.split("\\+|i");
        int ar = Integer.parseInt(a[0]), ai = Integer.parseInt(a[1]);
        int br = Integer.parseInt(b[0]), bi = Integer.parseInt(b[1]);
        return String.format("%d+%di",ar*br -ai*bi, ar*bi + ai*br);        
    }
}

3. Complex Number Multiplication Solution JavaScript

var complexNumberMultiply = function(num1, num2) {
	var a = parseInt(num1.split("+")[0]);
	var b = parseInt(num1.split("+")[1].replace("i", ""));
	var c = parseInt(num2.split("+")[0]);
	var d = parseInt(num2.split("+")[1].replace("i", ""));
	return `${a * c - b * d}+${a * d + b * c}i`;    
};

4. Complex Number Multiplication Solution Python

class Solution(object):
    def complexNumberMultiply(self, num1, num2):
        a, b = int(num1[:num1.index("+")]), int(num1[num1.index("+")+1:-1])
        c, d = int(num2[:num2.index("+")]), int(num2[num2.index("+")+1:-1])
        real_part = a * c - b * d
        imag_part = a * d + b * c
        result = str(real_part) + "+" + str(imag_part) + "i"
        return result