POJ 1775 Sum of Factorials 数论，基础题

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;

int main()
{
    //freopen("in.txt","r",stdin);
    int n;
    int a[11];
    memset(a,0,sizeof(a));
    a[0]=a[1]=1;
    for(int i=2; i<=10; i++)
        a[i]=i*a[i-1];
    while(scanf("%d",&n))
    {
        if(n<0)
            break;
        bool flag=true;
        if(n!=0)
            for(int i=10; i>0; i--)
            {
                if(n<=a[i] && n>=a[i-1])
                    n-=a[i-1];
                if(n==0)
                {
                    flag=false;
                    break;
                }
            }
        if(flag)
            printf("NO\n");
        else
            printf("YES\n");
    }
    return 0;
}