OJ_1124

#include <iostream>
using namespace std;
const int N=101;
int ctoi(char c)
{
    return c-'0';
}

int getresult(string s)
{
    int sum=0;
    
                  for(int i=0;i<s.size();i++)
                  {
                          int k=ctoi(s[i]);
                          sum+=k;
                  }
    int result=0;
    while(sum>=10)
    {
                  while(sum){
                             result+=sum%10;
                             sum/=10; 
                 }
                 sum=result;
                 result=0;
    }    
    
    return sum;
   
}
void func()
{
     string s;
     while(cin>>s)
     {
                  if(s=="0")break;
                  int result=getresult(s);
                  cout<<result<<endl;
     }
     
}
int main(int argc, char *argv[])
{
    
	//printf("Hello, world\n");
	func();
	return 0;
}

题目描述：

    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.
// 例如，考虑正数24，分解成2和4，和为6，6是单个数字，所以6就是24的数字根源；再考虑39，3与9的和是12，12不是单个数字，再分解一次，1与2的和是3，所以39的根源是3

输入：

    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.

输出：

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

样例输入：

24
39
0

样例输出：

6
3

提示：

The integer may consist of a large number of digits.