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- Complex Number Multiplication
Given two strings representing two [complex numbers].
You need to return a string representing their multiplication. Note i^2 = -1 according to the definition.
Example
Example 1:
Input: “1+1i”, “1+1i”
Output: “0+2i”
Explanation: (1 + i) * (1 + i) = 1 + i^2 + 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 + i^2 - 2 * i = -2i, and you need convert it to the form of 0±2i.
Notice
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.
这题好像主要考string的操作:
- int to string 用 to_string()
- string to int 用 stoi()
- string.find_first_of() 返回第一个出现的字符的位置。
代码如下 ：
class Solution {
public:
/**
* @param a: a string
* @param b: a string
* @return: a string representing their multiplication
*/
string complexNumberMultiply(string &a, string &b) {
string aR, bR;
string aV, bV;
size_t pos;
pos = a.find_first_of('+');
aR = a.substr(0, pos);
aV = a.substr(pos + 1);
aV.pop_back(); //remove 'i', the same as aV = aV.sub_str(0, aV.size() - 1);
pos = b.find_first_of('+');
bR = b.substr(0, pos);
bV = b.substr(pos + 1);
bV.pop_back();
int aR_int = stoi(aR);
int aV_int = stoi(aV);
int bR_int = stoi(bR);
int bV_int = stoi(bV);
return to_string(aR_int * bR_int - aV_int * bV_int) +
"+" +
to_string(aR_int * bV_int + aV_int * bR_int) +
"i";
}
};