OJ刷题记录：问题 D: 只出现一次的字符

#include <iostream>
#include <string>

using namespace std;

char getOnlyOneChar(string str) {
    char res;
    bool isOnlyOne = false;
    string son;
    int LEN = str.size();
    
    for (int i = 0; i < LEN; i++) {
        son = str.substr(0, i) + str.substr(i + 1);
        
        if (son.find(str[i]) == son.npos) {
            isOnlyOne = true;
            res = str[i];
            break;
        }
    }
    
    if (isOnlyOne == false) {
        res = '*';
    }
    
    return res;
}

int main() {
    string str, son;
    
    getline(cin, str);
    
    int LEN = str.size();
    
    for (int i = 1; i <= LEN; i++) {
        son = str.substr(0, i);
        cout << getOnlyOneChar(son);
    }
    
    return 0;
}