问题描述
Given two strings representing two
complex numbers.
You need to return a string representing their multiplication. Note i²
= -1 according to the definition.
Example

Input: "1+1i", "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.

/**
 * @param {string} a
 * @param {string} b
 * @return {string}
 */
var complexNumberMultiply = function(a, b) {
    var a1 = a.split("+");
    var b1 = b.split("+");
    var a2 = a1[1].split("i");
    var b2 = b1[1].split("i");
    console.log(a1,a2);
    return a1[0]*b1[0]-a2[0]*b2[0] + "+" + (a1[0]*b2[0]+a2[0]*b1[0])+"i";
};