[LeetCode]537. Complex Number Multiplication

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:

1. The input strings will not have extra blank.
2. 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.

public class Solution {
    public String complexNumberMultiply(String a, String b) {
        int[] aa=new int[2];
        int[] bb=new int[2];
        
        String[] aas;
        String[] bbs;
        
        int shi, xu;
        String output;

        aas=a.split("[+]");
        bbs=b.split("[+]");
        
        aa[0]=Integer.parseInt(aas[0]);
        aa[1]=Integer.parseInt(aas[1].split("i")[0]);
        bb[0]=Integer.parseInt(bbs[0]);
        bb[1]=Integer.parseInt(bbs[1].split("i")[0]);
    
  
        shi=aa[0]*bb[0]+(-1)*aa[1]*bb[1];
        xu=aa[0]*bb[1]+aa[1]*bb[0];
        
        output=shi+"+"+xu+"i";

        return output;
        
    }
}

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题目本身并不难，主要是对Java的语言还不是很熟悉。

一开始居然想用public String substring(int beginIndex)这个函数来做……

以及踩的一个坑：

java.util.regex.PatternSyntaxException: Dangling meta character '+' near index 0

，+、*、|、\等符号在正则表达示中有相应的不同意义。
一般来讲只需要加[]、或是\\即可
改成"sdfasdf+asdfasdf".split("[+]")