537. Complex Number Multiplication

待我称王封你为后i 2022-05-23 00:41 153阅读 0赞

/\*  
 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.  
  
\*/  
//先把字符串从+号分隔开，然后去除字符i，之后加起来就行了  
class Solution \{  
    public String complexNumberMultiply(String a, String b) \{  
        String\[\] num1 = a.split("\\\\+");  
        String\[\] num2 = b.split("\\\\+");  
        String num =null;  
        num1\[1\] = num1\[1\].replaceAll("i", "");  
        num2\[1\] = num2\[1\].replaceAll("i", "");  
        int a1 = Integer.valueOf(num1\[0\])\*Integer.valueOf(num2\[0\]);  
        int a2 = Integer.valueOf(num1\[1\])\*Integer.valueOf(num2\[0\]);  
        int a3 = Integer.valueOf(num1\[0\])\*Integer.valueOf(num2\[1\]);  
        int a4 = Integer.valueOf(num1\[1\])\*Integer.valueOf(num2\[1\]);  
        return String.valueOf(a1-a4)+"+"+String.valueOf(a3+a2)+"i";  
    \}  
\}