11332 - Summing Digits

http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=2307

f(n) = 1+2+3+4+5+6+7+8+9+2 = 47 f(f(n)) = 4+7 = 11 f(f(f(n))) = 1+1 = 2

一直重复做，直到是单位数

#include<stdio.h>

int main(){

    long n,t,sum=0;

    while(scanf("%ld",&n)!=EOF){

    if(n==0)break;

    while(n/10)是个位数，返回0；

    {t=n;     sum=0;

    while(t/10)

    {sum+=t%10;

    t=t/10;

    }

n=sum+t;

}

printf("%ld\n",n);

} return 0;

}