Problem:
Given two strings representing two complex numbers.
You need to return a string representing their multiplication. Note i2 = -1 according to the definition.
Example 1:
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.
Example 2:
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.
Note:
The input strings will not have extra blank.The input strings will be given in the form of a+bi, where the integer a and b will both belong to the range of [-100, 100]. And the output should be also in this form. Code: public class Solution { public String complexNumberMultiply(String a, String b) { String[] A = a.split("\\+"); //先把原String劈开 String[] B = b.split("\\+"); int a1 = Integer.valueOf(A[0]); int a2 = Integer.valueOf(A[1].replace("i","")); //挑出每个数字，学会用replace（）函数操作String； int b1 = Integer.valueOf(B[0]); int b2 = Integer.valueOf(B[1].replace("i","")); Integer c1 = a1 * b1 - a2 * b2; //必须用封装类型 Integer c2 = a1 * b2 + a2 * b1; return c1.toString() + "+" + c2.toString() + "i"; //因为基本型不能作为对象； } }