The digital root of a positive integer is found by summing the digits of the integer. If the resulting value is a single digit then that digit is the digital root. If the resulting value contains two or more digits, those digits are summed and the process is repeated. This is continued as long as necessary to obtain a single digit.

For example, consider the positive integer 24. Adding the 2 and the 4 yields a value of 6. Since 6 is a single digit, 6 is the digital root of 24. Now consider the positive integer 39. Adding the 3 and the 9 yields 12. Since 12 is not a single digit, the process must be repeated. Adding the 1 and the 2 yeilds 3, a single digit and also the digital root of 39.
 

Input
The input file will contain a list of positive integers, one per line. The end of the input will be indicated by an integer value of zero.
 

Output
For each integer in the input, output its digital root on a separate line of the output.
 

Sample Input
24
39
0
 

Sample Output
6
3

#include<stdio.h>
int main()
{
    int n,sum=0;
    while(scanf("%d",&n)!=EOF&&n!=0)
    {
        sum=0;
        while(n!=0)
        {
            sum+=n%10;
            n/=10;
            if(sum>10&&n==0)
            {    
                n=sum;
                sum=0;
            }
        }
        printf("%d\n",sum);
    }
    return 0;
}

我这个程序为什么通过不了的，，显示Wrong answer

这个程序应该不行，，在输入38的时候，即sum大于9的时候，还是会输出sum，再去计算，，，这样就不符合题意了

这个也过不了！