求教大佬帮忙看下哪里有问题啊＞﹏＜

C++ 14(GCC 9):

#include<iostream>
using namespace std;
int main()
{
	char a[13];
	int arr[10];
	for (int i = 0; i < 13; i++)
	{
		cin >> a[i];
	}

	int j = 0;
	for (int i = 0; i < 13; i++)
	{
		if (i == 1 || i == 5 || i == 11)
		{
			continue;
		}
		else
		{
			arr[j] = a[i] - '0';  // arr 里存的是ISBN里的数字（不包括"-"）
			j++;
		}
	}

	int len = 0;
	int x = 1;
	for (int i = 0; i < 9; i++)
	{
		len = len + arr[i] * x;
		x++;
	}
	len = len % 11;

	if (arr[9] == len)
	{
		cout << "Right";
	}
	else
	{
		arr[9] = len;

		cout << arr[0] << "-";
		for (int i = 1; i < 4; i++)
		{
			cout << arr[i];
		}
		cout << "-";

		for (int i = 4; i < 9; i++)
		{
			cout << arr[i];
		}
		cout << "-";

		if (arr[9] == 10)
		{
			cout << "X";
		}
		else
		{
			cout << arr[9];
		}
	}

	return 0;
}