我已在 “建议提供练习题 ”发表了这个题！但是我想问一下要给一个很大的数据要如何处理呢？
Digital Roots
Background
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.
Example
Input
24
39
0
Output
6
3
这是我写的代码！写的不好！请指教一下！对于很大的数据要如何来处理啊！谢谢了！
#include <stdio.h>
#include <stdlib.h>
int main()
{
long num, root;
scanf("%ld", &num);
while(num != 0)
{
long sum_integer(long num);
root = sum_integer(num);
while(root > 10)
{
root = sum_integer(root);
}
printf("%ld\n", root);
scanf("%ld", &num);
}
return 0;
}
long sum_integer(long num)
{
int i;
long g = 0;
for(i = 0;;i ++)
{
if(num < 10)
break;
g += num%10;
num = num/10;
}
g += num;
return g;
}
