闭眼码代码，莫名其妙就得了100。望大神指错。

#include<iostream>
#include<cstring>
using namespace std;
int a[100000],n,i,y,xy[100000],s[100000];
void add()
{
    int i;
    memset(xy,0,sizeof(xy));
    xy[0]=max(s[0],a[0]);
    for (i=1;i<=xy[0];i++)
    {
        xy[i]+=s[i]+a[i];
        xy[i+1]=xy[i]/10;
        xy[i]%=10;
        }
    while (xy[xy[0]+1]>0) 
        {
            xy[xy[0]+2]=xy[xy[0]+1]/10;
            xy[xy[0]+1]%=10;
            xy[0]++;
        }
    s[0]=xy[0];
    for (i=1;i<=xy[0];i++) s[i]=xy[i];
}
int main()
{
    cin>>n;
    a[0]=1;
    a[1]=1;
    s[0]=1;
    s[1]=0;
    for (y=1;y<=n;y++) 
    {
        memset(xy,0,sizeof(xy));
        xy[0]=a[0];
        for (i=1;i<=a[0];i++)
        {
          xy[i]+=a[i]*y;
          xy[i+1]=xy[i]/10;
          xy[i]%=10;
        }
        while (xy[xy[0]+1]>0) 
        {
            xy[xy[0]+2]=xy[xy[0]+1]/10;
            xy[xy[0]+1]%=10;
            xy[0]++;
        }
        for (i=1;i<=xy[0];i++) a[i]=xy[i];
        a[0]=xy[0];
        add();
    }
    for (i=s[0];i>=1;i--) cout<<s[i];
    cout<<endl;
    return 0;
}