各个位数相加，直到结果为一位数，返回这个结果

#include <stdio.h>
#include <stdlib.h>
int fun(int num){
  int temp = num;
  int sum =0;
  if(temp / 10 == 0){
    return temp;
  }
  while(temp != 0) {
    sum += temp % 10;
    temp /= 10;  
  }
  return fun(sum);  
}
int main() {
  int num =482;
  printf("%d",fun(num));
  return 0;
}