Less taolu, more sincerity.
You just copy and paste this code and you will get AC!
#include<iostream>
using namespace std;
const long long mod = 1e9+7;
long long func(int x){
if (x==1||x==0){
return 1;
}
return (x*func(x-1)+(x-1)*func(x-2))%mod;
}
int n;
int main(){
cin>>n;
cout<<func(n);
return 0;
}
Input only a single
integer n.
Please output
the answer by this code.
0<=N<=1e5