ISBN号码题解

#include <bits/stdc++.h>
using namespace std;
int main(){
	string s;
	cin >> s;
	int cnt = 1,sum = 0;
	for(int i = 0;i < s.size() - 1;i ++){
		if(s[i] >= '0' && s[i] <= '9'){
			sum = sum + (s[i] - '0') * cnt;
			cnt ++;
		}
	}
	sum %= 11;
	char ans;
	if(sum == 10) ans = 'X';
	else ans = sum + '0';
	if(s[s.size() - 1] == ans)cout << "Right" << endl;
	else{
		for(int i = 0;i < s.size() - 1;i ++)cout << s[i]; 
		cout << ans;
    }
	return 0;
}