Time Limit: 2000/1000 MS
(Java/Others) Memory Limit: 65536/32768 K
(Java/Others)
Total Submission(s): 13566 Accepted
Submission(s): 5660
1 #include <iostream>
2 using namespace std;
3 long long f(int n)
4 {
5 if(n==1)
6 return 0;
7 if(n==2)
8 return 1;
9 return (n-1)*(f(n-1)+f(n-2));
10 }
11 int main()
12 {
13 int n;
14 while(cin>>n){
15 cout<<f(n)<<endl;
16 }
17 return 0;
18 }
Freecode : www.cnblogs.com/yym2013
hdu 1465:不容易系列之一（递推入门题）,布布扣,bubuko.com
原文：http://www.cnblogs.com/yym2013/p/3680266.html