#include <stdio.h>
long fun(long x)//求阶乘
{
    return x<2?1:x*fun(x-1);   
}
int main()//假如n等于某阶乘和就输出YES 否则 NO
{
    long n,sum;
    int state, i;
    while(scanf("ld",&n)&&n>0)
    {
        state=sum=0;
        for(i=1;i<=n;i++)
        {
            sum+=fun(i);
            if(sum==n) {state=1;break;}
        }
        if(state) printf("YES\n");
        else    printf("NO\n");
    }
    return 0;
}

为什么我 输入9 就结束了？？？？应该输出YES的

哦 谢了~