题解 | The Biggest Water Problem

#include <stdio.h>

int out(int n)
{
    int g=0;
    while(n)
    {
        g+=n%10;
        n/=10;
    }
    if(g>9)
    {
        return out(g);
    }
    else
        return g;
}


int main()
{
    int n;
    scanf("%d",&n);
    printf("%d",out(n));
    return 0;
}