TJ

相当的基础

#include <iostream>
#include <string>
using namespace std;
int main() {
    string isbn;
    cin >> isbn;
    string digits;
    char check_digit;
    for (char c : isbn) {
        if (isdigit(c)) {
            if (digits.length() < 9) {
                digits += c;
            } else {
                check_digit = c;
                break;
            }
        }
    }

    int sum = 0;
    for (int i = 0; i < 9; ++i) {
        int digit = digits[i] - '0';
        sum += digit * (i + 1);
    }
    int remainder = sum % 11;
    char correct_check = (remainder == 10) ? 'X' : ('0' + remainder);
    if (check_digit == correct_check) {
        cout << "Right" << endl;
    } else {
        for (int i = 0; i < isbn.length() - 1; ++i) {
            cout << isbn[i];
        }
        cout << correct_check << endl;
    }
    return 0;
}