题解 | ISBN号码

#include <stdio.h>

int main()
{
	char isbn[15];
	scanf("%s",&isbn);
	
	int sum = 0,weight = 1;
	for(int i = 0;i<11;i++)
	{
         if(isbn[i] != '-')
         {
         	int digit = isbn[i] - '0';
         	sum += digit * weight;
         	weight++;
		 }
	}
	int reminder = sum % 11;
	char correct;
	if(reminder == 10)
	{
		correct = 'X';
	}
	else
	{
		correct = reminder + '0';
	}
	
	char original = isbn[12];
	if(original == correct)
	{
		printf("Right\n");
	}
	else
	{
		isbn[12] =  correct;
		printf("%s\n",isbn);
	}
	return 0;
}