算法入门【The Biggest Water Problem】

Thinking Process

use recurssion to calculate every digit sum. if sum < 10 return ,else calculate

Code

#include<stdio.h>

int f(int n) {
  if(n < 10) return n;
  int sum = 0;
  while(n) {
    int t = n % 10;
    sum += t;
    n /= 10;
  }
  return f(sum);
}
int main() {
  int n;
  scanf("%d", &n);
  printf("%d", f(n));
}