题目

记录

#include<bits/stdc++.h>
using namespace std;
const int MAXN=110;
struct gj{
	int n;
	int a[MAXN];
	gj(){
		n=1;
		memset(a,0,sizeof(a));
	}
	void fuzhi(int x){
		int k=0;
		while(x>0){
			a[++k]=x%10;
			x/=10;
		}
	}
	void shch(){
		for(int i=n;i>=1;--i){
			cout<<a[i];
		}
		cout<<'\n'/*' '*/;
	}
}ans;
gj operator+(const gj &a,const gj &b){
	gj c;
	c.n=max(a.n,b.n)+1;
	for(int i=1;i<=c.n;++i){
		c.a[i]+=a.a[i]+b.a[i];
	}
	for(int i=1;i<=c.n;++i){
		c.a[i+1]+=c.a[i]/10;
		c.a[i]=c.a[i]%10;
	}
	if(!c.a[c.n]) --c.n;
	return c;
}
gj operator*(const gj &a,const int &b){
	gj c;
	c.n=a.n+2;
	for(int i=1;i<=a.n;++i){
		c.a[i]=b*a.a[i];
	}
	for(int i=1;i<=c.n;++i){
		c.a[i+1]+=c.a[i]/10;
		c.a[i]=c.a[i]%10;
	}
	while(c.n>1){
		if(!c.a[c.n]) --c.n;
	}
	return c;
}
int n;
gj jc[55];
int main(){
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	cin>>n;
	jc[1].fuzhi(1);
	ans.fuzhi(1);
	for(int i=2;i<=n;++i){
		jc[i]=jc[i-1]*i;
		ans=ans+jc[i];
	}
	ans.shch();
	return 0;
}

自己完全看不出哪里超时了……请求大佬为我指路orz